draft-ietf-anima-grasp-12.txt   draft-ietf-anima-grasp-13.txt 
Network Working Group C. Bormann Network Working Group C. Bormann
Internet-Draft Universitaet Bremen TZI Internet-Draft Universitaet Bremen TZI
Intended status: Standards Track B. Carpenter, Ed. Intended status: Standards Track B. Carpenter, Ed.
Expires: November 20, 2017 Univ. of Auckland Expires: December 8, 2017 Univ. of Auckland
B. Liu, Ed. B. Liu, Ed.
Huawei Technologies Co., Ltd Huawei Technologies Co., Ltd
May 19, 2017 June 6, 2017
A Generic Autonomic Signaling Protocol (GRASP) A Generic Autonomic Signaling Protocol (GRASP)
draft-ietf-anima-grasp-12 draft-ietf-anima-grasp-13
Abstract Abstract
This document establishes requirements for a signaling protocol that This document specifies the GeneRic Autonomic Signaling Protocol
enables autonomic nodes and autonomic service agents to dynamically (GRASP), which enables autonomic nodes and autonomic service agents
discover peers, to synchronize state with them, and to negotiate to dynamically discover peers, to synchronize state with each other,
parameter settings with them. The document then defines a general and to negotiate parameter settings with each other. GRASP depends
protocol for discovery, synchronization and negotiation, while the on an external security environment that is described elsewhere. The
technical objectives for specific scenarios are to be described in technical objectives and parameters for specific application
separate documents. An Appendix briefly discusses existing protocols scenarios are to be described in separate documents. Appendices
briefly discuss requirements for the protocol and existing protocols
with comparable features. with comparable features.
Status of This Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirement Analysis of Discovery, Synchronization and 2. GRASP Protocol Overview . . . . . . . . . . . . . . . . . . . 5
Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements for Discovery . . . . . . . . . . . . . . . 5 2.2. High Level Deployment Model . . . . . . . . . . . . . . . 7
2.2. Requirements for Synchronization and Negotiation 2.3. High Level Design . . . . . . . . . . . . . . . . . . . . 8
Capability . . . . . . . . . . . . . . . . . . . . . . . 6 2.4. Quick Operating Overview . . . . . . . . . . . . . . . . 11
2.3. Specific Technical Requirements . . . . . . . . . . . . . 9 2.5. GRASP Protocol Basic Properties and Mechanisms . . . . . 12
3. GRASP Protocol Overview . . . . . . . . . . . . . . . . . . . 10 2.5.1. Required External Security Mechanism . . . . . . . . 12
3.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 10 2.5.2. Constrained Instances . . . . . . . . . . . . . . . . 12
3.2. High Level Deployment Model . . . . . . . . . . . . . . . 12 2.5.3. Transport Layer Usage . . . . . . . . . . . . . . . . 14
3.3. High Level Design Choices . . . . . . . . . . . . . . . . 13 2.5.4. Discovery Mechanism and Procedures . . . . . . . . . 14
3.4. Quick Operating Overview . . . . . . . . . . . . . . . . 16 2.5.5. Negotiation Procedures . . . . . . . . . . . . . . . 18
3.5. GRASP Protocol Basic Properties and Mechanisms . . . . . 17 2.5.6. Synchronization and Flooding Procedures . . . . . . . 20
3.5.1. Required External Security Mechanism . . . . . . . . 17 2.6. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 22
3.5.2. Constrained Instances . . . . . . . . . . . . . . . . 17 2.7. Session Identifier (Session ID) . . . . . . . . . . . . . 23
3.5.3. Transport Layer Usage . . . . . . . . . . . . . . . . 19 2.8. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 23
3.5.4. Discovery Mechanism and Procedures . . . . . . . . . 20 2.8.1. Message Overview . . . . . . . . . . . . . . . . . . 23
3.5.5. Negotiation Procedures . . . . . . . . . . . . . . . 23 2.8.2. GRASP Message Format . . . . . . . . . . . . . . . . 24
3.5.6. Synchronization and Flooding Procedures . . . . . . . 25 2.8.3. Message Size . . . . . . . . . . . . . . . . . . . . 25
3.6. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 27 2.8.4. Discovery Message . . . . . . . . . . . . . . . . . . 25
3.7. Session Identifier (Session ID) . . . . . . . . . . . . . 28 2.8.5. Discovery Response Message . . . . . . . . . . . . . 26
3.8. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 29 2.8.6. Request Messages . . . . . . . . . . . . . . . . . . 27
3.8.1. Message Overview . . . . . . . . . . . . . . . . . . 29 2.8.7. Negotiation Message . . . . . . . . . . . . . . . . . 28
3.8.2. GRASP Message Format . . . . . . . . . . . . . . . . 29 2.8.8. Negotiation End Message . . . . . . . . . . . . . . . 29
3.8.3. Message Size . . . . . . . . . . . . . . . . . . . . 30 2.8.9. Confirm Waiting Message . . . . . . . . . . . . . 29
3.8.4. Discovery Message . . . . . . . . . . . . . . . . . . 30 2.8.10. Synchronization Message . . . . . . . . . . . . . . . 29
3.8.5. Discovery Response Message . . . . . . . . . . . . . 31 2.8.11. Flood Synchronization Message . . . . . . . . . . . . 30
3.8.6. Request Messages . . . . . . . . . . . . . . . . . . 32 2.8.12. Invalid Message . . . . . . . . . . . . . . . . . . . 31
3.8.7. Negotiation Message . . . . . . . . . . . . . . . . . 34 2.8.13. No Operation Message . . . . . . . . . . . . . . . . 31
3.8.8. Negotiation End Message . . . . . . . . . . . . . . . 34 2.9. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 31
3.8.9. Confirm Waiting Message . . . . . . . . . . . . . 34 2.9.1. Format of GRASP Options . . . . . . . . . . . . . . . 31
3.8.10. Synchronization Message . . . . . . . . . . . . . . . 35 2.9.2. Divert Option . . . . . . . . . . . . . . . . . . . . 32
3.8.11. Flood Synchronization Message . . . . . . . . . . . . 35 2.9.3. Accept Option . . . . . . . . . . . . . . . . . . . . 32
3.8.12. Invalid Message . . . . . . . . . . . . . . . . . . . 36 2.9.4. Decline Option . . . . . . . . . . . . . . . . . . . 32
3.8.13. No Operation Message . . . . . . . . . . . . . . . . 36 2.9.5. Locator Options . . . . . . . . . . . . . . . . . . . 33
3.9. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 36 2.10. Objective Options . . . . . . . . . . . . . . . . . . . . 35
3.9.1. Format of GRASP Options . . . . . . . . . . . . . . . 37 2.10.1. Format of Objective Options . . . . . . . . . . . . 35
3.9.2. Divert Option . . . . . . . . . . . . . . . . . . . . 37 2.10.2. Objective flags . . . . . . . . . . . . . . . . . . 36
3.9.3. Accept Option . . . . . . . . . . . . . . . . . . . . 37 2.10.3. General Considerations for Objective Options . . . . 36
3.9.4. Decline Option . . . . . . . . . . . . . . . . . . . 37 2.10.4. Organizing of Objective Options . . . . . . . . . . 37
3.9.5. Locator Options . . . . . . . . . . . . . . . . . . . 38 2.10.5. Experimental and Example Objective Options . . . . . 39
3.10. Objective Options . . . . . . . . . . . . . . . . . . . . 40 3. Implementation Status [RFC Editor: please remove] . . . . . . 39
3.10.1. Format of Objective Options . . . . . . . . . . . . 40 3.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 39
3.10.2. Objective flags . . . . . . . . . . . . . . . . . . 41 3.2. Python Implementation . . . . . . . . . . . . . . . . . . 40
3.10.3. General Considerations for Objective Options . . . . 41 4. Security Considerations . . . . . . . . . . . . . . . . . . . 41
3.10.4. Organizing of Objective Options . . . . . . . . . . 42 5. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 43
3.10.5. Experimental and Example Objective Options . . . . . 44 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 45
4. Implementation Status [RFC Editor: please remove] . . . . . . 44 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 47
4.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 44 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.2. Python Implementation . . . . . . . . . . . . . . . . . . 45 8.1. Normative References . . . . . . . . . . . . . . . . . . 47
5. Security Considerations . . . . . . . . . . . . . . . . . . . 46 8.2. Informative References . . . . . . . . . . . . . . . . . 48
6. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 48
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 52
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
9.1. Normative References . . . . . . . . . . . . . . . . . . 52
9.2. Informative References . . . . . . . . . . . . . . . . . 53
Appendix A. Open Issues [RFC Editor: This section should be Appendix A. Open Issues [RFC Editor: This section should be
empty. Please remove] . . . . . . . . . . . . . . . 57 empty. Please remove] . . . . . . . . . . . . . . . 52
Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 57 Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 52
Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 65 Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 61
Appendix D. Example Message Formats . . . . . . . . . . . . . . 72 Appendix D. Example Message Formats . . . . . . . . . . . . . . 68
D.1. Discovery Example . . . . . . . . . . . . . . . . . . . . 72 D.1. Discovery Example . . . . . . . . . . . . . . . . . . . . 68
D.2. Flood Example . . . . . . . . . . . . . . . . . . . . . . 73 D.2. Flood Example . . . . . . . . . . . . . . . . . . . . . . 69
D.3. Synchronization Example . . . . . . . . . . . . . . . . . 73 D.3. Synchronization Example . . . . . . . . . . . . . . . . . 69
D.4. Simple Negotiation Example . . . . . . . . . . . . . . . 73 D.4. Simple Negotiation Example . . . . . . . . . . . . . . . 69
D.5. Complete Negotiation Example . . . . . . . . . . . . . . 74 D.5. Complete Negotiation Example . . . . . . . . . . . . . . 70
Appendix E. Capability Analysis of Current Protocols . . . . . . 75 Appendix E. Requirement Analysis of Discovery, Synchronization
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 77 and Negotiation . . . . . . . . . . . . . . . . . . 71
E.1. Requirements for Discovery . . . . . . . . . . . . . . . 71
E.2. Requirements for Synchronization and Negotiation
Capability . . . . . . . . . . . . . . . . . . . . . . . 73
E.3. Specific Technical Requirements . . . . . . . . . . . . . 75
Appendix F. Capability Analysis of Current Protocols . . . . . . 76
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 78
1. Introduction 1. Introduction
The success of the Internet has made IP-based networks bigger and The success of the Internet has made IP-based networks bigger and
more complicated. Large-scale ISP and enterprise networks have more complicated. Large-scale ISP and enterprise networks have
become more and more problematic for human based management. Also, become more and more problematic for human based management. Also,
operational costs are growing quickly. Consequently, there are operational costs are growing quickly. Consequently, there are
increased requirements for autonomic behavior in the networks. increased requirements for autonomic behavior in the networks.
General aspects of autonomic networks are discussed in [RFC7575] and General aspects of autonomic networks are discussed in [RFC7575] and
[RFC7576]. [RFC7576].
skipping to change at page 4, line 12 skipping to change at page 4, line 13
In order to fulfill autonomy, devices that embody Autonomic Service In order to fulfill autonomy, devices that embody Autonomic Service
Agents (ASAs, [RFC7575]) have specific signaling requirements. In Agents (ASAs, [RFC7575]) have specific signaling requirements. In
particular they need to discover each other, to synchronize state particular they need to discover each other, to synchronize state
with each other, and to negotiate parameters and resources directly with each other, and to negotiate parameters and resources directly
with each other. There is no limitation on the types of parameters with each other. There is no limitation on the types of parameters
and resources concerned, which can include very basic information and resources concerned, which can include very basic information
needed for addressing and routing, as well as anything else that needed for addressing and routing, as well as anything else that
might be configured in a conventional non-autonomic network. The might be configured in a conventional non-autonomic network. The
atomic unit of discovery, synchronization or negotiation is referred atomic unit of discovery, synchronization or negotiation is referred
to as a technical objective, i.e, a configurable parameter or set of to as a technical objective, i.e, a configurable parameter or set of
parameters (defined more precisely in Section 3.1). parameters (defined more precisely in Section 2.1).
Following this Introduction, Section 2 describes the requirements for Negotiation is an iterative process, requiring multiple message
discovery, synchronization and negotiation. Negotiation is an exchanges forming a closed loop between the negotiating entities. In
iterative process, requiring multiple message exchanges forming a fact, these entities are ASAs, normally but not necessarily in
closed loop between the negotiating entities. In fact, these different network devices. State synchronization, when needed, can
entities are ASAs, normally but not necessarily in different network be regarded as a special case of negotiation, without iteration.
devices. State synchronization, when needed, can be regarded as a Both negotiation and synchronization must logically follow discovery.
special case of negotiation, without iteration. Section 3.3 More details of the requirements are found in Appendix E.
describes a behavior model for a protocol intended to support Section 2.3 describes a behavior model for a protocol intended to
discovery, synchronization and negotiation. The design of GeneRic support discovery, synchronization and negotiation. The design of
Autonomic Signaling Protocol (GRASP) in Section 3 of this document is GeneRic Autonomic Signaling Protocol (GRASP) in Section 2 of this
based on this behavior model. The relevant capabilities of various document is based on this behavior model. The relevant capabilities
existing protocols are reviewed in Appendix E. of various existing protocols are reviewed in Appendix F.
The proposed discovery mechanism is oriented towards synchronization The proposed discovery mechanism is oriented towards synchronization
and negotiation objectives. It is based on a neighbor discovery and negotiation objectives. It is based on a neighbor discovery
process on the local link, but also supports diversion to peers on process on the local link, but also supports diversion to peers on
other links. There is no assumption of any particular form of other links. There is no assumption of any particular form of
network topology. When a device starts up with no pre-configuration, network topology. When a device starts up with no pre-configuration,
it has no knowledge of the topology. The protocol itself is capable it has no knowledge of the topology. The protocol itself is capable
of being used in a small and/or flat network structure such as a of being used in a small and/or flat network structure such as a
small office or home network as well as in a large professionally small office or home network as well as in a large professionally
managed network. Therefore, the discovery mechanism needs to be able managed network. Therefore, the discovery mechanism needs to be able
skipping to change at page 5, line 5 skipping to change at page 5, line 5
Because GRASP can be used as part of a decision process among Because GRASP can be used as part of a decision process among
distributed devices or between networks, it must run in a secure and distributed devices or between networks, it must run in a secure and
strongly authenticated environment. strongly authenticated environment.
In realistic deployments, not all devices will support GRASP. In realistic deployments, not all devices will support GRASP.
Therefore, some autonomic service agents will directly manage a group Therefore, some autonomic service agents will directly manage a group
of non-autonomic nodes, and other non-autonomic nodes will be managed of non-autonomic nodes, and other non-autonomic nodes will be managed
traditionally. Such mixed scenarios are not discussed in this traditionally. Such mixed scenarios are not discussed in this
specification. specification.
2. Requirement Analysis of Discovery, Synchronization and Negotiation 2. GRASP Protocol Overview
This section discusses the requirements for discovery, negotiation
and synchronization capabilities. The primary user of the protocol
is an autonomic service agent (ASA), so the requirements are mainly
expressed as the features needed by an ASA. A single physical device
might contain several ASAs, and a single ASA might manage several
technical objectives. If a technical objective is managed by several
ASAs, any necessary coordination is outside the scope of the GRASP
signaling protocol. Furthermore, requirements for ASAs themselves,
such as the processing of Intent [RFC7575], are out of scope for the
present document.
2.1. Requirements for Discovery
D1. ASAs may be designed to manage any type of configurable device
or software, as required in Section 2.2. A basic requirement is
therefore that the protocol can represent and discover any kind of
technical objective among arbitrary subsets of participating nodes.
In an autonomic network we must assume that when a device starts up
it has no information about any peer devices, the network structure,
or what specific role it must play. The ASA(s) inside the device are
in the same situation. In some cases, when a new application session
starts up within a device, the device or ASA may again lack
information about relevant peers. For example, it might be necessary
to set up resources on multiple other devices, coordinated and
matched to each other so that there is no wasted resource. Security
settings might also need updating to allow for the new device or
user. The relevant peers may be different for different technical
objectives. Therefore discovery needs to be repeated as often as
necessary to find peers capable of acting as counterparts for each
objective that a discovery initiator needs to handle. From this
background we derive the next three requirements:
D2. When an ASA first starts up, it may have no knowledge of the
specific network to which it is attached. Therefore the discovery
process must be able to support any network scenario, assuming only
that the device concerned is bootstrapped from factory condition.
D3. When an ASA starts up, it must require no configured location
information about any peers in order to discover them.
D4. If an ASA supports multiple technical objectives, relevant peers
may be different for different discovery objectives, so discovery
needs to be performed separately to find counterparts for each
objective. Thus, there must be a mechanism by which an ASA can
separately discover peer ASAs for each of the technical objectives
that it needs to manage, whenever necessary.
D5. Following discovery, an ASA will normally perform negotiation or
synchronization for the corresponding objectives. The design should
allow for this by conveniently linking discovery to negotiation and
synchronization. It may provide an optional mechanism to combine
discovery and negotiation/synchronization in a single protocol
exchange.
D6. Some objectives may only be significant on the local link, but
others may be significant across the routed network and require off-
link operations. Thus, the relevant peers might be immediate
neighbors on the same layer 2 link, or they might be more distant and
only accessible via layer 3. The mechanism must therefore provide
both on-link and off-link discovery of ASAs supporting specific
technical objectives.
D7. The discovery process should be flexible enough to allow for
special cases, such as the following:
o During initialization, a device must be able to establish mutual
trust with the rest of the network and participate in an
authentication mechanism. Although this will inevitably start
with a discovery action, it is a special case precisely because
trust is not yet established. This topic is the subject of
[I-D.ietf-anima-bootstrapping-keyinfra]. We require that once
trust has been established for a device, all ASAs within the
device inherit the device's credentials and are also trusted.
This does not preclude the device having multiple credentials.
o Depending on the type of network involved, discovery of other
central functions might be needed, such as the Network Operations
Center (NOC) [I-D.ietf-anima-stable-connectivity]. The protocol
must be capable of supporting such discovery during
initialization, as well as discovery during ongoing operation.
D8. The discovery process must not generate excessive traffic and
must take account of sleeping nodes.
D9. There must be a mechanism for handling stale discovery results.
2.2. Requirements for Synchronization and Negotiation Capability
As background, consider the example of routing protocols, the closest
approximation to autonomic networking already in widespread use.
Routing protocols use a largely autonomic model based on distributed
devices that communicate repeatedly with each other. The focus is
reachability, so routing protocols primarily consider simple link
status and metrics, and an underlying assumption is that nodes need a
consistent, although partial, view of the network topology in order
for the routing algorithm to converge. Also, routing is mainly based
on simple information synchronization between peers, rather than on
bi-directional negotiation.
By contrast, autonomic networks need to be able to manage many
different types of parameter and consider many more dimensions, such
as latency, load, unused or limited resources, conflicting resource
requests, security settings, power saving, load balancing, etc.
Status information and resource metrics need to be shared between
nodes for dynamic adjustment of resources and for monitoring
purposes. While this might be achieved by existing protocols when
they are available, the new protocol needs to be able to support
parameter exchange, including mutual synchronization, even when no
negotiation as such is required. In general, these parameters do not
apply to all participating nodes, but only to a subset.
SN1. A basic requirement for the protocol is therefore the ability
to represent, discover, synchronize and negotiate almost any kind of
network parameter among selected subsets of participating nodes.
SN2. Negotiation is an iterative request/response process that must
be guaranteed to terminate (with success or failure). While tie-
breaking rules must be defined specifically for each use case, the
protocol should have some general mechanisms in support of loop and
deadlock prevention, such as hop count limits or timeouts.
SN3. Synchronization must be possible for groups of nodes ranging
from small to very large.
SN4. To avoid "reinventing the wheel", the protocol should be able
to encapsulate the data formats used by existing configuration
protocols (such as NETCONF/YANG) in cases where that is convenient.
SN5. Human intervention in complex situations is costly and error-
prone. Therefore, synchronization or negotiation of parameters
without human intervention is desirable whenever the coordination of
multiple devices can improve overall network performance. It follows
that the protocol's resource requirements must be appropriate for any
device that would otherwise need human intervention. The issue of
running in constrained nodes is discussed in
[I-D.ietf-anima-reference-model].
SN6. Human intervention in large networks is often replaced by use
of a top-down network management system (NMS). It therefore follows
that the protocol, as part of the Autonomic Networking
Infrastructure, should be capable of running in any device that would
otherwise be managed by an NMS, and that it can co-exist with an NMS,
and with protocols such as SNMP and NETCONF.
SN7. Some features are expected to be implemented by individual
ASAs, but the protocol must be general enough to allow them:
o Dependencies and conflicts: In order to decide upon a
configuration for a given device, the device may need information
from neighbors. This can be established through the negotiation
procedure, or through synchronization if that is sufficient.
However, a given item in a neighbor may depend on other
information from its own neighbors, which may need another
negotiation or synchronization procedure to obtain or decide.
Therefore, there are potential dependencies and conflicts among
negotiation or synchronization procedures. Resolving dependencies
and conflicts is a matter for the individual ASAs involved. To
allow this, there need to be clear boundaries and convergence
mechanisms for negotiations. Also some mechanisms are needed to
avoid loop dependencies or uncontrolled growth in a tree of
dependencies. It is the ASA designer's responsibility to avoid or
detect looping dependencies or excessive growth of dependency
trees. The protocol's role is limited to bilateral signaling
between ASAs, and the avoidance of loops during bilateral
signaling.
o Recovery from faults and identification of faulty devices should
be as automatic as possible. The protocol's role is limited to
discovery, synchronization and negotiation. These processes can
occur at any time, and an ASA may need to repeat any of these
steps when the ASA detects an event such as a negotiation
counterpart failing.
o Since a major goal is to minimize human intervention, it is
necessary that the network can in effect "think ahead" before
changing its parameters. One aspect of this is an ASA that relies
on a knowledge base to predict network behavior. This is out of
scope for the signaling protocol. However, another aspect is
forecasting the effect of a change by a "dry run" negotiation
before actually installing the change. Signaling a dry run is
therefore a desirable feature of the protocol.
Note that management logging, monitoring, alerts and tools for
intervention are required. However, these can only be features of
individual ASAs, not of the protocol itself. Another document
[I-D.ietf-anima-stable-connectivity] discusses how such agents may be
linked into conventional OAM systems via an Autonomic Control Plane
[I-D.ietf-anima-autonomic-control-plane].
SN8. The protocol will be able to deal with a wide variety of
technical objectives, covering any type of network parameter.
Therefore the protocol will need a flexible and easily extensible
format for describing objectives. At a later stage it may be
desirable to adopt an explicit information model. One consideration
is whether to adopt an existing information model or to design a new
one.
2.3. Specific Technical Requirements
T1. It should be convenient for ASA designers to define new
technical objectives and for programmers to express them, without
excessive impact on run-time efficiency and footprint. In
particular, it should be convenient for ASAs to be implemented
independently of each other as user space programs rather than as
kernel code, where such a programming model is possible. The classes
of device in which the protocol might run is discussed in
[I-D.ietf-anima-reference-model].
T2. The protocol should be easily extensible in case the initially
defined discovery, synchronization and negotiation mechanisms prove
to be insufficient.
T3. To be a generic platform, the protocol payload format should be
independent of the transport protocol or IP version. In particular,
it should be able to run over IPv6 or IPv4. However, some functions,
such as multicasting on a link, might need to be IP version
dependent. By default, IPv6 should be preferred.
T4. The protocol must be able to access off-link counterparts via
routable addresses, i.e., must not be restricted to link-local
operation.
T5. It must also be possible for an external discovery mechanism to
be used, if appropriate for a given technical objective. In other
words, GRASP discovery must not be a prerequisite for GRASP
negotiation or synchronization.
T6. The protocol must be capable of distinguishing multiple
simultaneous operations with one or more peers, especially when wait
states occur.
T7. Intent: Although the distribution of Intent is out of scope for
this document, the protocol must not by design exclude its use for
Intent distribution.
T8. Management monitoring, alerts and intervention: Devices should
be able to report to a monitoring system. Some events must be able
to generate operator alerts and some provision for emergency
intervention must be possible (e.g. to freeze synchronization or
negotiation in a mis-behaving device). These features might not use
the signaling protocol itself, but its design should not exclude such
use.
T9. Because this protocol may directly cause changes to device
configurations and have significant impacts on a running network, all
protocol exchanges need to be fully secured against forged messages
and man-in-the middle attacks, and secured as much as reasonably
possible against denial of service attacks. There must also be an
encryption mechanism to resist unwanted monitoring. However, it is
not required that the protocol itself provides these security
features; it may depend on an existing secure environment.
3. GRASP Protocol Overview
3.1. Terminology 2.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119] when they appear in ALL CAPS. When these words are not in [RFC2119] when they appear in ALL CAPS. When these words are not in
ALL CAPS (such as "should" or "Should"), they have their usual ALL CAPS (such as "should" or "Should"), they have their usual
English meanings, and are not to be interpreted as [RFC2119] key English meanings, and are not to be interpreted as [RFC2119] key
words. words.
This document uses terminology defined in [RFC7575]. This document uses terminology defined in [RFC7575].
skipping to change at page 11, line 9 skipping to change at page 5, line 42
the current state of parameter values stored in other ASAs. This the current state of parameter values stored in other ASAs. This
is a special case of negotiation in which information is sent but is a special case of negotiation in which information is sent but
the ASAs do not request their peers to change parameter settings. the ASAs do not request their peers to change parameter settings.
All other definitions apply to both negotiation and All other definitions apply to both negotiation and
synchronization. synchronization.
o Technical Objective (usually abbreviated as Objective): A o Technical Objective (usually abbreviated as Objective): A
technical objective is a data structure, whose main contents are a technical objective is a data structure, whose main contents are a
name and a value. The value consists of a single configurable name and a value. The value consists of a single configurable
parameter or a set of parameters of some kind. The exact format parameter or a set of parameters of some kind. The exact format
of an objective is defined in Section 3.10.1. An objective occurs of an objective is defined in Section 2.10.1. An objective occurs
in three contexts: Discovery, Negotiation and Synchronization. in three contexts: Discovery, Negotiation and Synchronization.
Normally, a given objective will not occur in negotiation and Normally, a given objective will not occur in negotiation and
synchronization contexts simultaneously. synchronization contexts simultaneously.
* One ASA may support multiple independent objectives. * One ASA may support multiple independent objectives.
* The parameter(s) in the value of a given objective apply to a * The parameter(s) in the value of a given objective apply to a
specific service or function or action. They may in principle specific service or function or action. They may in principle
be anything that can be set to a specific logical, numerical or be anything that can be set to a specific logical, numerical or
string value, or a more complex data structure, by a network string value, or a more complex data structure, by a network
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* Synchronization Objective: an objective whose specific * Synchronization Objective: an objective whose specific
technical content needs to be synchronized among two or more technical content needs to be synchronized among two or more
ASAs. Thus, each ASA will maintain its own copy of the ASAs. Thus, each ASA will maintain its own copy of the
objective. objective.
* Negotiation Objective: an objective whose specific technical * Negotiation Objective: an objective whose specific technical
content needs to be decided in coordination with another ASA. content needs to be decided in coordination with another ASA.
Again, each ASA will maintain its own copy of the objective. Again, each ASA will maintain its own copy of the objective.
A detailed discussion of objectives, including their format, is A detailed discussion of objectives, including their format, is
found in Section 3.10. found in Section 2.10.
o Discovery Initiator: an ASA that starts discovery by sending a o Discovery Initiator: an ASA that starts discovery by sending a
discovery message referring to a specific discovery objective. discovery message referring to a specific discovery objective.
o Discovery Responder: a peer that either contains an ASA supporting o Discovery Responder: a peer that either contains an ASA supporting
the discovery objective indicated by the discovery initiator, or the discovery objective indicated by the discovery initiator, or
caches the locator(s) of the ASA(s) supporting the objective. It caches the locator(s) of the ASA(s) supporting the objective. It
sends a Discovery Response, as described later. sends a Discovery Response, as described later.
o Synchronization Initiator: an ASA that starts synchronization by o Synchronization Initiator: an ASA that starts synchronization by
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request message referring to a specific negotiation objective. request message referring to a specific negotiation objective.
o Negotiation Counterpart: a peer with which the Negotiation o Negotiation Counterpart: a peer with which the Negotiation
Initiator negotiates a specific negotiation objective. Initiator negotiates a specific negotiation objective.
o GRASP Instance: This refers to an instantiation of a GRASP o GRASP Instance: This refers to an instantiation of a GRASP
protocol engine, likely including multiple threads or processes as protocol engine, likely including multiple threads or processes as
well as dynamic data structures such as a discovery cache, running well as dynamic data structures such as a discovery cache, running
in a given security environment on a single device. in a given security environment on a single device.
o GRASP Core: This refers to the code and shared data structures of
a GRASP instance, which will communicate with individual ASAs via
a suitable Application Programming Interface (API).
o Interface or GRASP Interface: Unless otherwise stated, these refer o Interface or GRASP Interface: Unless otherwise stated, these refer
to a network interface - which might be physical or virtual - that to a network interface - which might be physical or virtual - that
a specific instance of GRASP is currently using. A device might a specific instance of GRASP is currently using. A device might
have other interfaces that are not used by GRASP and which are have other interfaces that are not used by GRASP and which are
outside the scope of the autonomic network. outside the scope of the autonomic network.
3.2. High Level Deployment Model 2.2. High Level Deployment Model
A GRASP implementation will be part of the Autonomic Networking A GRASP implementation will be part of the Autonomic Networking
Infrastructure in an autonomic node, which must also provide an Infrastructure in an autonomic node, which must also provide an
appropriate security environment. In accordance with appropriate security environment. In accordance with
[I-D.ietf-anima-reference-model], this SHOULD be the Autonomic [I-D.ietf-anima-reference-model], this SHOULD be the Autonomic
Control Plane (ACP) [I-D.ietf-anima-autonomic-control-plane]. It is Control Plane (ACP) [I-D.ietf-anima-autonomic-control-plane]. As a
expected that GRASP will access the ACP by using a typical socket result, all autonomic nodes in the ACP are able to trust each other.
programming interface and the ACP will make available only network It is expected that GRASP will access the ACP by using a typical
interfaces within the autonomic network. If there is no ACP, the socket programming interface and the ACP will make available only
considerations described in Section 3.5.1 apply. network interfaces within the autonomic network. If there is no ACP,
the considerations described in Section 2.5.1 apply.
There will also be one or more Autonomic Service Agents (ASAs). In There will also be one or more Autonomic Service Agents (ASAs). In
the minimal case of a single-purpose device, these components might the minimal case of a single-purpose device, these components might
be fully integrated with GRASP and the ACP. A more common model is be fully integrated with GRASP and the ACP. A more common model is
expected to be a multi-purpose device capable of containing several expected to be a multi-purpose device capable of containing several
ASAs. In this case it is expected that the ACP, GRASP and the ASAs ASAs, such as a router or large switch. In this case it is expected
will be implemented as separate processes, which are probably multi- that the ACP, GRASP and the ASAs will be implemented as separate
threaded to support asynchronous and simultaneous operations. processes, which are able to support asynchronous and simultaneous
operations, for example by multi-threading.
In some scenarios, a limited negotiation model might be deployed In some scenarios, a limited negotiation model might be deployed
based on a limited trust relationship such as that between two based on a limited trust relationship such as that between two
administrative domains. ASAs might then exchange limited information administrative domains. ASAs might then exchange limited information
and negotiate some particular configurations. and negotiate some particular configurations.
GRASP is explicitly designed to operate within a single addressing GRASP is explicitly designed to operate within a single addressing
realm. Its discovery and flooding mechanisms do not support realm. Its discovery and flooding mechanisms do not support
autonomic operations that cross any form of address translator or autonomic operations that cross any form of address translator or
upper layer proxy. upper layer proxy.
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In the presence of the ACP, such information will be available from In the presence of the ACP, such information will be available from
the adjacency table discussed in [I-D.ietf-anima-reference-model]. the adjacency table discussed in [I-D.ietf-anima-reference-model].
In other cases, GRASP must determine such information for itself. In other cases, GRASP must determine such information for itself.
Details depend on the device and operating system. In the rest of Details depend on the device and operating system. In the rest of
this document, the terms 'interfaces' or 'GRASP interfaces' refers this document, the terms 'interfaces' or 'GRASP interfaces' refers
only to the set of network interfaces that a specific instance of only to the set of network interfaces that a specific instance of
GRASP is currently using. GRASP is currently using.
Because GRASP needs to work with very high reliability, especially Because GRASP needs to work with very high reliability, especially
during bootstrapping and during fault conditions, it is essential during bootstrapping and during fault conditions, it is essential
that every implementation is as robust as possible. For example, that every implementation continues to operate in adverse conditions.
discovery failures, or any kind of socket exception at any time, must For example, discovery failures, or any kind of socket exception at
not cause irrecoverable failures in GRASP itself, and must return any time, must not cause irrecoverable failures in GRASP itself, and
suitable error codes through the API so that ASAs can also recover. must return suitable error codes through the API so that ASAs can
also recover.
GRASP must not depend upon non-volatile data storage. All run time GRASP must not depend upon non-volatile data storage. All run time
error conditions, and events such as address renumbering, network error conditions, and events such as address renumbering, network
interface failures, and CPU sleep/wake cycles, must be handled in interface failures, and CPU sleep/wake cycles, must be handled in
such a way that GRASP will still operate correctly and securely such a way that GRASP will still operate correctly and securely
(Section 3.5.1) afterwards. (Section 2.5.1) afterwards.
An autonomic node will normally run a single instance of GRASP, used An autonomic node will normally run a single instance of GRASP, used
by multiple ASAs. Possible exceptions are mentioned below. by multiple ASAs. Possible exceptions are mentioned below.
3.3. High Level Design Choices 2.3. High Level Design
This section describes a behavior model and design choices for GRASP, This section describes the behavior model and general design of
supporting discovery, synchronization and negotiation, to act as a GRASP, supporting discovery, synchronization and negotiation, to act
platform for different technical objectives. as a platform for different technical objectives.
o A generic platform: o A generic platform:
The protocol design is generic and independent of the The protocol design is generic and independent of the
synchronization or negotiation contents. The technical contents synchronization or negotiation contents. The technical contents
will vary according to the various technical objectives and the will vary according to the various technical objectives and the
different pairs of counterparts. different pairs of counterparts.
o Normally, a single main instance of the GRASP protocol engine will o Normally, a single main instance of the GRASP protocol engine will
exist in an autonomic node, and each ASA will run as an exist in an autonomic node, and each ASA will run as an
independent asynchronous process. However, scenarios where independent asynchronous process. However, scenarios where
multiple instances of GRASP run in a single node, perhaps with multiple instances of GRASP run in a single node, perhaps with
different security properties, are possible (Section 3.5.2). In different security properties, are possible (Section 2.5.2). In
this case, each instance MUST listen independently for GRASP link- this case, each instance MUST listen independently for GRASP link-
local multicasts, and all instances MUST be woken by each such local multicasts, and all instances MUST be woken by each such
multicast, in order for discovery and flooding to work correctly. multicast, in order for discovery and flooding to work correctly.
o Security infrastructure: o Security infrastructure:
As noted above, the protocol itself has no built-in security As noted above, the protocol itself has no built-in security
functionality, and relies on a separate secure infrastructure. functionality, and relies on a separate secure infrastructure.
o Discovery, synchronization and negotiation are designed together: o Discovery, synchronization and negotiation are designed together:
The discovery method and the synchronization and negotiation The discovery method and the synchronization and negotiation
methods are designed in the same way and can be combined when this methods are designed in the same way and can be combined when this
is useful, allowing a rapid mode of operation described in is useful, allowing a rapid mode of operation described in
Section 3.5.4. These processes can also be performed Section 2.5.4. These processes can also be performed
independently when appropriate. independently when appropriate.
* Thus, for some objectives, especially those concerned with * Thus, for some objectives, especially those concerned with
application layer services, another discovery mechanism such as application layer services, another discovery mechanism such as
the future DNS Service Discovery [RFC7558] MAY be used. The the future DNS Service Discovery [RFC7558] MAY be used. The
choice is left to the designers of individual ASAs. choice is left to the designers of individual ASAs.
o A uniform pattern for technical objectives: o A uniform pattern for technical objectives:
The synchronization and negotiation objectives are defined The synchronization and negotiation objectives are defined
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condition in a negotiation step reply, it should be as close as condition in a negotiation step reply, it should be as close as
possible to the original request or previous suggestion. The possible to the original request or previous suggestion. The
suggested value of later negotiation steps should be chosen suggested value of later negotiation steps should be chosen
between the suggested values from the previous two steps. GRASP between the suggested values from the previous two steps. GRASP
provides mechanisms to guarantee convergence (or failure) in a provides mechanisms to guarantee convergence (or failure) in a
small number of steps, namely a timeout and a maximum number of small number of steps, namely a timeout and a maximum number of
iterations. iterations.
o Extensibility: o Extensibility:
GRASP does not have a version number, and could be extended by GRASP intentionally does not have a version number, and can be
adding new message types and options. In normal use, new extended by adding new message types and options. The Invalid
semantics will be added by defining new synchronization or Message (M_INVALID) will be used to signal that an implementation
negotiation objectives. does not recognize a message or option sent by another
implementation. In normal use, new semantics will be added by
defining new synchronization or negotiation objectives.
3.4. Quick Operating Overview 2.4. Quick Operating Overview
An instance of GRASP is expected to run as a separate core module, An instance of GRASP is expected to run as a separate core module,
providing an API (such as [I-D.liu-anima-grasp-api]) to interface to providing an API (such as [I-D.liu-anima-grasp-api]) to interface to
various ASAs. These ASAs may operate without special privilege, various ASAs. These ASAs may operate without special privilege,
unless they need it for other reasons (such as configuring IP unless they need it for other reasons (such as configuring IP
addresses or manipulating routing tables). addresses or manipulating routing tables).
The GRASP mechanisms used by the ASA are built around GRASP The GRASP mechanisms used by the ASA are built around GRASP
objectives defined as data structures containing administrative objectives defined as data structures containing administrative
information such as the objective's unique name, and its current information such as the objective's unique name, and its current
value. The format and size of the value is not restricted by the value. The format and size of the value is not restricted by the
protocol, except that it must be possible to serialise it for protocol, except that it must be possible to serialize it for
transmission in CBOR, which is no restriction at all in practice. transmission in CBOR, which is no restriction at all in practice.
GRASP provides the following mechanisms: GRASP provides the following mechanisms:
o A discovery mechanism (M_DISCOVERY, M_RESPONSE), by which an ASA o A discovery mechanism (M_DISCOVERY, M_RESPONSE), by which an ASA
can discover other ASAs supporting a given objective. can discover other ASAs supporting a given objective.
o A negotiation request mechanism (M_REQ_NEG), by which an ASA can o A negotiation request mechanism (M_REQ_NEG), by which an ASA can
start negotiation of an objective with a counterpart ASA. Once a start negotiation of an objective with a counterpart ASA. Once a
negotiation has started, the process is symmetrical, and there is negotiation has started, the process is symmetrical, and there is
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o A flood mechanism (M_FLOOD), by which an ASA can cause the current o A flood mechanism (M_FLOOD), by which an ASA can cause the current
value of an objective to be flooded throughout the autonomic value of an objective to be flooded throughout the autonomic
network so that any ASA can receive it. One application of this network so that any ASA can receive it. One application of this
is to act as an announcement, avoiding the need for discovery of a is to act as an announcement, avoiding the need for discovery of a
widely applicable objective. widely applicable objective.
Some example messages and simple message flows are provided in Some example messages and simple message flows are provided in
Appendix D. Appendix D.
3.5. GRASP Protocol Basic Properties and Mechanisms 2.5. GRASP Protocol Basic Properties and Mechanisms
3.5.1. Required External Security Mechanism 2.5.1. Required External Security Mechanism
The protocol SHOULD always run within a secure Autonomic Control The protocol SHOULD always run within a secure Autonomic Control
Plane (ACP) [I-D.ietf-anima-autonomic-control-plane]. The ACP is Plane (ACP) [I-D.ietf-anima-autonomic-control-plane]. The ACP is
assumed to carry all messages securely, including link-local assumed to carry all messages securely, including link-local
multicast when it is virtualized over the ACP. A GRASP instance MUST multicast when it is virtualized over the ACP. A GRASP instance MUST
verify whether the ACP is operational. verify whether the ACP is operational.
If there is no ACP, one of the following alternatives applies: If there is no ACP, one of the alternatives in Section 2.5.2 applies.
1. The protocol instance MUST use another form of strong
authentication and a form of strong encryption MUST be
implemented. An exception is that during initialization of nodes
there will be a transition period during which it might not be
practical to run with strong encryption. This period MUST be as
short as possible, changing to a fully secure setup as soon as
possible. See Section 3.5.2.1 for further discussion.
2. The protocol instance MUST operate as described in
Section 3.5.2.2 or Section 3.5.2.3.
Network interfaces could be at different security levels, for example Network interfaces could be at different security levels, in
being part of the ACP or not. All the interfaces supported by a particular being part of the ACP or not. All the interfaces
given GRASP instance MUST be at the same security level. supported by a given GRASP instance MUST be at the same security
level.
The ACP, or in its absence another security mechanism, sets the The ACP, or in its absence another security mechanism, sets the
boundary within which nodes are trusted as GRASP peers. A GRASP boundary within which nodes are trusted as GRASP peers. A GRASP
implementation MUST refuse to execute GRASP synchronization and implementation MUST refuse to execute GRASP synchronization and
negotiation functions if there is neither an operational ACP nor negotiation functions if there is neither an operational ACP nor
another secure environment. another secure environment.
Link-local multicast is used for discovery messages. Responses to Link-local multicast is used for discovery messages. Responses to
discovery messages MUST be secured, with one exception mentioned in discovery messages MUST be secured, with one exception mentioned in
the next section. the next section.
3.5.2. Constrained Instances 2.5.2. Constrained Instances
This section describes some cases where additional instances of GRASP This section describes some cases where additional instances of GRASP
subject to certain constraints are appropriate. are appropriate, subject to certain security constraints.
3.5.2.1. No ACP In these cases, since multicast packets are not secured, Rapid Mode
discovery (Section 2.5.4.5) MUST NOT be used.
As mentioned in Section 3.3, some GRASP operations might be performed 2.5.2.1. No ACP
As mentioned in Section 2.3, some GRASP operations might be performed
across an administrative domain boundary by mutual agreement, without across an administrative domain boundary by mutual agreement, without
the benefit of an ACP. Such operations MUST be confined to a the benefit of an ACP. Such operations MUST be confined to a
separate instance of GRASP with its own copy of all GRASP data separate instance of GRASP with its own copy of all GRASP data
structures. Messages MUST be authenticated and encryption MUST be structures. Messages MUST be authenticated and encryption MUST be
implemented. TLS [RFC5246] and DTLS [RFC6347] based on a Public Key used. Further details may be specified in future documents.
Infrastructure (PKI) [RFC5280] are RECOMMENDED for this purpose.
Further details are out of scope for this document.
3.5.2.2. Discovery Unsolicited Link-Local 2.5.2.2. Discovery Unsolicited Link-Local
Some services may need to use insecure GRASP discovery, response and Some services may need to use insecure GRASP discovery, response and
flood messages without being able to use pre-existing security flood messages without being able to use pre-existing security
associations. Such operations being intrinsically insecure, they associations. Such operations being intrinsically insecure, they
need to be confined to link-local use to minimize the risk of need to be confined to link-local use to minimize the risk of
malicious actions. Possible examples include discovery of candidate malicious actions. Possible examples include discovery of candidate
ACP neighbors [I-D.ietf-anima-autonomic-control-plane], discovery of ACP neighbors [I-D.ietf-anima-autonomic-control-plane], discovery of
bootstrap proxies [I-D.ietf-anima-bootstrapping-keyinfra] or perhaps bootstrap proxies [I-D.ietf-anima-bootstrapping-keyinfra] or perhaps
initialization services in networks using GRASP without being fully initialization services in networks using GRASP without being fully
autonomic (e.g., no ACP). Such usage MUST be limited to link-local autonomic (e.g., no ACP). Such usage MUST be limited to link-local
operations and MUST be confined to a separate insecure instance of operations on a single interface and MUST be confined to a separate
GRASP with its own copy of all GRASP data structures. This instance insecure instance of GRASP with its own copy of all GRASP data
is nicknamed DULL - Discovery Unsolicited Link-Local. structures. This instance is nicknamed DULL - Discovery Unsolicited
Link-Local.
The detailed rules for the DULL instance of GRASP are as follows: The detailed rules for the DULL instance of GRASP are as follows:
o An initiator MUST only send Discovery or Flood Synchronization o An initiator MAY send Discovery or Flood Synchronization link-
link-local multicast messages with a loop count of 1. Other GRASP local multicast messages which MUST have a loop count of 1, to
message types MUST NOT be sent. prevent off-link operations. Other GRASP message types MUST NOT
be sent.
o A responder MUST silently discard any message whose loop count is o A responder MUST silently discard any message whose loop count is
not 1. not 1.
o A responder MUST silently discard any message referring to a GRASP o A responder MUST silently discard any message referring to a GRASP
Objective that is not directly part of a service that requires Objective that is not directly part of a service that requires
this insecure mode. this insecure mode.
o A responder MUST NOT relay any multicast messages. o A responder MUST NOT relay any multicast messages.
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o A node MUST silently discard any message whose source address is o A node MUST silently discard any message whose source address is
not link-local. not link-local.
To minimize traffic possibly observed by third parties, GRASP traffic To minimize traffic possibly observed by third parties, GRASP traffic
SHOULD be minimized by using only Flood Synchronization to announce SHOULD be minimized by using only Flood Synchronization to announce
objectives and their associated locators, rather than by using objectives and their associated locators, rather than by using
Discovery and Response. Further details are out of scope for this Discovery and Response. Further details are out of scope for this
document document
3.5.2.3. Secure Only Neighbor Negotiation 2.5.3. Transport Layer Usage
Some services might use insecure on-link operations as in DULL, but
also use unicast synchronization or negotiation operations protected
by TLS. A separate instance of GRASP is used, with its own copy of
all GRASP data structures. This instance is nicknamed SONN - Secure
Only Neighbor Negotiation.
The detailed rules for the SONN instance of GRASP are as follows:
o All types of GRASP message are permitted.
o An initiator MUST send any Discovery or Flood Synchronization
link-local multicast messages with a loop count of 1.
o A responder MUST silently discard any Discovery or Flood
Synchronization message whose loop count is not 1.
o A responder MUST silently discard any message referring to a GRASP
Objective that is not directly part of the service concerned.
o A responder MUST NOT relay any multicast messages.
o A Discovery Response MUST indicate a link-local address.
o A Discovery Response MUST NOT include a Divert option.
o A node MUST silently discard any message whose source address is
not link-local.
Further details are out of scope for this document.
3.5.3. Transport Layer Usage All GRASP messages, after they are serialized as a CBOR byte string,
are transmitted as such directly over the transport protocol in use,
which itself runs within the security environment discussed in the
previous section.
GRASP discovery and flooding messages are designed for use over link- GRASP discovery and flooding messages are designed for use over link-
local multicast UDP. They MUST NOT be fragmented, and therefore MUST local multicast UDP. They MUST NOT be fragmented, and therefore MUST
NOT exceed the link MTU size. NOT exceed the link MTU size. An implementation should report any
attempt to send a longer message as a run-time error.
All other GRASP messages are unicast and could in principle run over All other GRASP messages are unicast and could in principle run over
any transport protocol. An implementation MUST support use of TCP. any transport protocol. An implementation MUST support use of TCP.
It MAY support use of another transport protocol but the details are It MAY support use of another transport protocol but the details are
out of scope for this specification. However, GRASP itself does not out of scope for this specification. However, GRASP itself does not
provide for error detection or retransmission. Use of an unreliable provide for error detection or retransmission. Use of an unreliable
transport protocol is therefore NOT RECOMMENDED. transport protocol is therefore NOT RECOMMENDED.
For considerations when running without an ACP, see Section 3.5.2.1. For considerations when running without an ACP, see Section 2.5.2.1.
For link-local multicast, the GRASP protocol listens to the well- For link-local multicast, the GRASP protocol listens to the well-
known GRASP Listen Port (Section 3.6). For unicast transport known GRASP Listen Port (Section 2.6). For unicast transport
sessions used for discovery responses, synchronization and sessions used for discovery responses, synchronization and
negotiation, the ASA concerned normally listens on its own negotiation, the ASA concerned normally listens on its own
dynamically assigned ports, which are communicated to its peers dynamically assigned ports, which are communicated to its peers
during discovery. However, a minimal implementation MAY use the during discovery. However, a minimal implementation MAY use the
GRASP Listen Port for this purpose. GRASP Listen Port for this purpose.
3.5.4. Discovery Mechanism and Procedures 2.5.4. Discovery Mechanism and Procedures
3.5.4.1. Separated discovery and negotiation mechanisms 2.5.4.1. Separated discovery and negotiation mechanisms
Although discovery and negotiation or synchronization are defined Although discovery and negotiation or synchronization are defined
together in GRASP, they are separate mechanisms. The discovery together in GRASP, they are separate mechanisms. The discovery
process could run independently from the negotiation or process could run independently from the negotiation or
synchronization process. Upon receiving a Discovery (Section 3.8.4) synchronization process. Upon receiving a Discovery (Section 2.8.4)
message, the recipient node should return a response message in which message, the recipient node should return a response message in which
it either indicates itself as a discovery responder or diverts the it either indicates itself as a discovery responder or diverts the
initiator towards another more suitable ASA. However, this response initiator towards another more suitable ASA. However, this response
may be delayed if the recipient needs to relay the discovery onwards, may be delayed if the recipient needs to relay the discovery onwards,
as described below. as described below.
The discovery action (M_DISCOVERY) will normally be followed by a The discovery action (M_DISCOVERY) will normally be followed by a
negotiation (M_REQ_NEG) or synchronization (M_REQ_SYN) action. The negotiation (M_REQ_NEG) or synchronization (M_REQ_SYN) action. The
discovery results could be utilized by the negotiation protocol to discovery results could be utilized by the negotiation protocol to
decide which ASA the initiator will negotiate with. decide which ASA the initiator will negotiate with.
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example, an ASA might perform discovery even if it only wishes to act example, an ASA might perform discovery even if it only wishes to act
a Synchronization Initiator or Negotiation Initiator. Such an ASA a Synchronization Initiator or Negotiation Initiator. Such an ASA
does not itself need to respond to discovery messages. does not itself need to respond to discovery messages.
It is also entirely possible to use GRASP discovery without any It is also entirely possible to use GRASP discovery without any
subsequent negotiation or synchronization action. In this case, the subsequent negotiation or synchronization action. In this case, the
discovered objective is simply used as a name during the discovery discovered objective is simply used as a name during the discovery
process and any subsequent operations between the peers are outside process and any subsequent operations between the peers are outside
the scope of GRASP. the scope of GRASP.
3.5.4.2. Discovery Overview 2.5.4.2. Discovery Overview
A complete discovery process will start with a multicast (of A complete discovery process will start with a multicast (of
M_DISCOVERY) on the local link. On-link neighbors supporting the M_DISCOVERY) on the local link. On-link neighbors supporting the
discovery objective will respond directly (with M_RESPONSE). A discovery objective will respond directly (with M_RESPONSE). A
neighbor with multiple interfaces will respond with a cached neighbor with multiple interfaces may respond with a cached discovery
discovery response if any. However, it SHOULD NOT respond with a response. If it has no cached response, it will relay the discovery
cached response on an interface if it learnt that information from on its other GRASP interfaces. If a node receiving the relayed
the same interface, because the peer in question will answer directly discovery supports the discovery objective, it will respond to the
if still operational. If it has no cached response, it will relay relayed discovery. If it has a cached response, it will respond with
the discovery on its other GRASP interfaces, for example reaching a that. If not, it will repeat the discovery process, which thereby
higher-level gateway in a hierarchical network. If a node receiving becomes iterative. The loop count and timeout will ensure that the
the relayed discovery supports the discovery objective, it will process ends. Further details are given below.
respond to the relayed discovery. If it has a cached response, it
will respond with that. If not, it will repeat the discovery
process, which thereby becomes iterative. The loop count and timeout
will ensure that the process ends.
A Discovery message MAY be sent unicast (via UDP or TCP) to a peer A Discovery message MAY be sent unicast (via UDP or TCP) to a peer
node, which SHOULD then proceed exactly as if the message had been node, which SHOULD then proceed exactly as if the message had been
multicast, except that when TCP is used, the response will be on the multicast, except that when TCP is used, the response will be on the
same socket as the query. However, this mode does not guarantee same socket as the query. However, this mode does not guarantee
successful discovery in the general case. successful discovery in the general case.
3.5.4.3. Discovery Procedures 2.5.4.3. Discovery Procedures
Discovery starts as an on-link operation. The Divert option can tell Discovery starts as an on-link operation. The Divert option can tell
the discovery initiator to contact an off-link ASA for that discovery the discovery initiator to contact an off-link ASA for that discovery
objective. A Discovery message is sent by a discovery initiator via objective. A Discovery message is sent by a discovery initiator via
UDP to the ALL_GRASP_NEIGHBORS link-local multicast address UDP to the ALL_GRASP_NEIGHBORS link-local multicast address
(Section 3.6). Every network device that supports GRASP always (Section 2.6). Every network device that supports GRASP always
listens to a well-known UDP port to capture the discovery messages. listens to a well-known UDP port to capture the discovery messages.
Because this port is unique in a device, this is a function of the Because this port is unique in a device, this is a function of the
GRASP instance and not of an individual ASA. As a result, each ASA GRASP instance and not of an individual ASA. As a result, each ASA
will need to register the objectives that it supports with the local will need to register the objectives that it supports with the local
GRASP instance. GRASP instance.
If an ASA in a neighbor device supports the requested discovery If an ASA in a neighbor device supports the requested discovery
objective, the device SHOULD respond to the link-local multicast with objective, the device SHOULD respond to the link-local multicast with
a unicast Discovery Response message (Section 3.8.5) with locator a unicast Discovery Response message (Section 2.8.5) with locator
option(s), unless it is temporarily unavailable. Otherwise, if the option(s), unless it is temporarily unavailable. Otherwise, if the
neighbor has cached information about an ASA that supports the neighbor has cached information about an ASA that supports the
requested discovery objective (usually because it discovered the same requested discovery objective (usually because it discovered the same
objective before), it SHOULD respond with a Discovery Response objective before), it SHOULD respond with a Discovery Response
message with a Divert option pointing to the appropriate Discovery message with a Divert option pointing to the appropriate Discovery
Responder. Responder. However, on a link that supports link-local multicast, it
SHOULD NOT respond with a cached response on an interface if it
learnt that information from the same interface, because the peer in
question will answer directly if still operational.
If a device has no information about the requested discovery If a device has no information about the requested discovery
objective, and is not acting as a discovery relay (see below) it MUST objective, and is not acting as a discovery relay (see below) it MUST
silently discard the Discovery message. silently discard the Discovery message.
If no discovery response is received within a reasonable timeout The discovery initiator MUST set a reasonable timeout on the
(default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the Discovery discovery process. A suggested value is 100 milliseconds multiplied
message MAY be repeated, with a newly generated Session ID by the loop count embedded in the objective.
(Section 3.7). An exponential backoff SHOULD be used for subsequent
repetitions, to limit the load during busy periods. Frequent If no discovery response is received within the timeout, the
repetition might be symptomatic of a denial of service attack. Discovery message MAY be repeated, with a newly generated Session ID
(Section 2.7). An exponential backoff SHOULD be used for subsequent
repetitions, to limit the load during busy periods. The details of
the backoff algorithm will depend on the use case for the objective
concerned but MUST be consistent with the recommendations in
[RFC8085] for low data-volume multicast. Frequent repetition might
be symptomatic of a denial of service attack.
After a GRASP device successfully discovers a locator for a Discovery After a GRASP device successfully discovers a locator for a Discovery
Responder supporting a specific objective, it MUST cache this Responder supporting a specific objective, it SHOULD cache this
information, including the interface index via which it was information, including the interface index [RFC3493] via which it was
discovered. This cache record MAY be used for future negotiation or discovered. This cache record MAY be used for future negotiation or
synchronization, and the locator SHOULD be passed on when appropriate synchronization, and the locator SHOULD be passed on when appropriate
as a Divert option to another Discovery Initiator. as a Divert option to another Discovery Initiator.
The cache mechanism MUST include a lifetime for each entry. The The cache mechanism MUST include a lifetime for each entry. The
lifetime is derived from a time-to-live (ttl) parameter in each lifetime is derived from a time-to-live (ttl) parameter in each
Discovery Response message. Cached entries MUST be ignored or Discovery Response message. Cached entries MUST be ignored or
deleted after their lifetime expires. In some environments, deleted after their lifetime expires. In some environments,
unplanned address renumbering might occur. In such cases, the unplanned address renumbering might occur. In such cases, the
lifetime SHOULD be short compared to the typical address lifetime and lifetime SHOULD be short compared to the typical address lifetime.
a mechanism to flush the discovery cache MUST be implemented. The The discovery mechanism needs to track the node's current address to
discovery mechanism needs to track the node's current address to
ensure that Discovery Responses always indicate the correct address. ensure that Discovery Responses always indicate the correct address.
If multiple Discovery Responders are found for the same objective, If multiple Discovery Responders are found for the same objective,
they SHOULD all be cached, unless this creates a resource shortage. they SHOULD all be cached, unless this creates a resource shortage.
The method of choosing between multiple responders is an The method of choosing between multiple responders is an
implementation choice. This choice MUST be available to each ASA but implementation choice. This choice MUST be available to each ASA but
the GRASP implementation SHOULD provide a default choice. the GRASP implementation SHOULD provide a default choice.
Because Discovery Responders will be cached in a finite cache, they Because Discovery Responders will be cached in a finite cache, they
might be deleted at any time. In this case, discovery will need to might be deleted at any time. In this case, discovery will need to
be repeated. If an ASA exits for any reason, its locator might still be repeated. If an ASA exits for any reason, its locator might still
be cached for some time, and attempts to connect to it will fail. be cached for some time, and attempts to connect to it will fail.
ASAs need to be robust in these circumstances. ASAs need to be robust in these circumstances.
3.5.4.4. Discovery Relaying 2.5.4.4. Discovery Relaying
A GRASP instance with multiple link-layer interfaces (typically A GRASP instance with multiple link-layer interfaces (typically
running in a router) MUST support discovery on all GRASP interfaces. running in a router) MUST support discovery on all GRASP interfaces.
We refer to this as a 'relaying instance'. We refer to this as a 'relaying instance'.
Constrained Instances (Section 3.5.2) are always single-interface Constrained Instances (Section 2.5.2) are always single-interface
instances and therefore MUST NOT perform discovery relaying. instances and therefore MUST NOT perform discovery relaying.
If a relaying instance receives a Discovery message on a given If a relaying instance receives a Discovery message on a given
interface for a specific objective that it does not support and for interface for a specific objective that it does not support and for
which it has not previously cached a Discovery Responder, it MUST which it has not previously cached a Discovery Responder, it MUST
relay the query by re-issuing a new Discovery message as a link-local relay the query by re-issuing a new Discovery message as a link-local
multicast on its other GRASP interfaces. multicast on its other GRASP interfaces.
The relayed discovery message MUST have the same Session ID as the The relayed discovery message MUST have the same Session ID as the
incoming discovery message and MUST be tagged with the IP address of incoming discovery message and MUST be tagged with the IP address of
its original initiator (see Section 3.8.4). Note that this initiator its original initiator (see Section 2.8.4). Note that this initiator
address is only used to allow for disambiguation of the Session ID address is only used to allow for disambiguation of the Session ID
and is never used to address Response packets, which are sent to the and is never used to address Response packets, which are sent to the
relaying instance, not the original initiator. relaying instance, not the original initiator.
Since the relay device is unaware of the timeout set by the original
initiator it SHOULD set a timeout at least equal to GRASP_DEF_TIMEOUT
milliseconds.
The relaying instance MUST decrement the loop count within the The relaying instance MUST decrement the loop count within the
objective, and MUST NOT relay the Discovery message if the result is objective, and MUST NOT relay the Discovery message if the result is
zero. Also, it MUST limit the total rate at which it relays zero. Also, it MUST limit the total rate at which it relays
discovery messages to a reasonable value, in order to mitigate discovery messages to a reasonable value, in order to mitigate
possible denial of service attacks. It MUST cache the Session ID possible denial of service attacks. For example, the rate limit
value and initiator address of each relayed Discovery message until could be set to a small multiple of the observed rate of discovery
any Discovery Responses have arrived or the discovery process has messages during normal operation. The relaying instance MUST cache
timed out. To prevent loops, it MUST NOT relay a Discovery message the Session ID value and initiator address of each relayed Discovery
which carries a given cached Session ID and initiator address more message until any Discovery Responses have arrived or the discovery
than once. These precautions avoid discovery loops and mitigate process has timed out. To prevent loops, it MUST NOT relay a
potential overload. Discovery message which carries a given cached Session ID and
initiator address more than once. These precautions avoid discovery
loops and mitigate potential overload.
Since the relay device is unaware of the timeout set by the original
initiator it SHOULD set a suitable timeout for the relayed discovery.
A suggested value is 100 milliseconds multiplied by the remaining
loop count.
The discovery results received by the relaying instance MUST in turn The discovery results received by the relaying instance MUST in turn
be sent as a Discovery Response message to the Discovery message that be sent as a Discovery Response message to the Discovery message that
caused the relay action. caused the relay action.
3.5.4.5. Rapid Mode (Discovery/Negotiation binding) 2.5.4.5. Rapid Mode (Discovery with Negotiation or Synchronization )
A Discovery message MAY include a Negotiation Objective option. This
allows a rapid mode of negotiation described in Section 3.5.5. A
similar mechanism is defined for synchronization in Section 3.5.6.
Note that rapid mode is currently limited to a single objective for A Discovery message MAY include an Objective option. This allows a
simplicity of design and implementation. A possible future extension rapid mode of negotiation (Section 2.5.5.1) or synchronization
is to allow multiple objectives in rapid mode for greater efficiency. (Section 2.5.6.3). Rapid mode is currently limited to a single
objective for simplicity of design and implementation. A possible
future extension is to allow multiple objectives in rapid mode for
greater efficiency.
3.5.5. Negotiation Procedures 2.5.5. Negotiation Procedures
A negotiation initiator sends a negotiation request (using M_REQ_NEG) A negotiation initiator opens a transport connection to a counterpart
to a counterpart ASA, including a specific negotiation objective. It ASA using the address, protocol and port obtained during discovery.
may request the negotiation counterpart to make a specific It then sends a negotiation request (using M_REQ_NEG) to the
configuration. Alternatively, it may request a certain simulation or counterpart, including a specific negotiation objective. It may
forecast result by sending a dry run configuration. The details, request the negotiation counterpart to make a specific configuration.
including the distinction between a dry run and a live configuration Alternatively, it may request a certain simulation or forecast result
change, will be defined separately for each type of negotiation by sending a dry run configuration. The details, including the
objective. Any state associated with a dry run operation, such as distinction between a dry run and a live configuration change, will
temporarily reserving a resource for subsequent use in a live run, is be defined separately for each type of negotiation objective. Any
entirely a matter for the designer of the ASA concerned. state associated with a dry run operation, such as temporarily
reserving a resource for subsequent use in a live run, is entirely a
matter for the designer of the ASA concerned.
Each negotiation session as a whole is subject to a timeout (default Each negotiation session as a whole is subject to a timeout (default
GRASP_DEF_TIMEOUT milliseconds, Section 3.6), initialised when the GRASP_DEF_TIMEOUT milliseconds, Section 2.6), initialised when the
request is sent (see Section 3.8.6). If no reply message of any kind request is sent (see Section 2.8.6). If no reply message of any kind
is received within a reasonable timeout, the negotiation request MAY is received within the timeout, the negotiation request MAY be
be repeated, with a newly generated Session ID (Section 3.7). An repeated, with a newly generated Session ID (Section 2.7). An
exponential backoff SHOULD be used for subsequent repetitions. exponential backoff SHOULD be used for subsequent repetitions. The
details of the backoff algorithm will depend on the use case for the
objective concerned.
If the counterpart can immediately apply the requested configuration, If the counterpart can immediately apply the requested configuration,
it will give an immediate positive (O_ACCEPT) answer (using M_END). it will give an immediate positive (O_ACCEPT) answer (using M_END).
This will end the negotiation phase immediately. Otherwise, it will This will end the negotiation phase immediately. Otherwise, it will
negotiate (using M_NEGOTIATE). It will reply with a proposed negotiate (using M_NEGOTIATE). It will reply with a proposed
alternative configuration that it can apply (typically, a alternative configuration that it can apply (typically, a
configuration that uses fewer resources than requested by the configuration that uses fewer resources than requested by the
negotiation initiator). This will start a bi-directional negotiation negotiation initiator). This will start a bi-directional negotiation
(using M_NEGOTIATE) to reach a compromise between the two ASAs. (using M_NEGOTIATE) to reach a compromise between the two ASAs.
The negotiation procedure is ended when one of the negotiation peers The negotiation procedure is ended when one of the negotiation peers
sends a Negotiation Ending (M_END) message, which contains an accept sends a Negotiation Ending (M_END) message, which contains an accept
(O_ACCEPT) or decline (O_DECLINE) option and does not need a response (O_ACCEPT) or decline (O_DECLINE) option and does not need a response
from the negotiation peer. Negotiation may also end in failure from the negotiation peer. Negotiation may also end in failure
(equivalent to a decline) if a timeout is exceeded or a loop count is (equivalent to a decline) if a timeout is exceeded or a loop count is
exceeded. exceeded. When the procedure ends for whatever reason, the transport
connection SHOULD be closed. A transport session failure is treated
as a negotiation failure.
A negotiation procedure concerns one objective and one counterpart. A negotiation procedure concerns one objective and one counterpart.
Both the initiator and the counterpart may take part in simultaneous Both the initiator and the counterpart may take part in simultaneous
negotiations with various other ASAs, or in simultaneous negotiations negotiations with various other ASAs, or in simultaneous negotiations
about different objectives. Thus, GRASP is expected to be used in a about different objectives. Thus, GRASP is expected to be used in a
multi-threaded mode. Certain negotiation objectives may have multi-threaded mode or its logical equivalent. Certain negotiation
restrictions on multi-threading, for example to avoid over-allocating objectives may have restrictions on multi-threading, for example to
resources. avoid over-allocating resources.
Some configuration actions, for example wavelength switching in Some configuration actions, for example wavelength switching in
optical networks, might take considerable time to execute. The ASA optical networks, might take considerable time to execute. The ASA
concerned needs to allow for this by design, but GRASP does allow for concerned needs to allow for this by design, but GRASP does allow for
a peer to insert latency in a negotiation process if necessary a peer to insert latency in a negotiation process if necessary
(Section 3.8.9, M_WAIT). (Section 2.8.9, M_WAIT).
3.5.5.1. Rapid Mode (Discovery/Negotiation Linkage) 2.5.5.1. Rapid Mode (Discovery/Negotiation Linkage)
A Discovery message MAY include a Negotiation Objective option. In A Discovery message MAY include a Negotiation Objective option. In
this case it is as if the initiator sent the sequence M_DISCOVERY, this case it is as if the initiator sent the sequence M_DISCOVERY,
immediately followed by M_REQ_NEG. This has implications for the immediately followed by M_REQ_NEG. This has implications for the
construction of the GRASP core, as it must carefully pass the construction of the GRASP core, as it must carefully pass the
contents of the Negotiation Objective option to the ASA so that it contents of the Negotiation Objective option to the ASA so that it
may evaluate the objective directly. When a Negotiation Objective may evaluate the objective directly. When a Negotiation Objective
option is present the ASA replies with an M_NEGOTIATE message (or option is present the ASA replies with an M_NEGOTIATE message (or
M_END with O_ACCEPT if it is immediately satisfied with the M_END with O_ACCEPT if it is immediately satisfied with the
proposal), rather than with an M_RESPONSE. However, if the recipient proposal), rather than with an M_RESPONSE. However, if the recipient
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It is possible that a Discovery Response will arrive from a responder It is possible that a Discovery Response will arrive from a responder
that does not support rapid mode, before such a Negotiation message that does not support rapid mode, before such a Negotiation message
arrives. In this case, rapid mode will not occur. arrives. In this case, rapid mode will not occur.
This rapid mode could reduce the interactions between nodes so that a This rapid mode could reduce the interactions between nodes so that a
higher efficiency could be achieved. However, a network in which higher efficiency could be achieved. However, a network in which
some nodes support rapid mode and others do not will have complex some nodes support rapid mode and others do not will have complex
timing-dependent behaviors. Therefore, the rapid negotiation timing-dependent behaviors. Therefore, the rapid negotiation
function SHOULD be disabled by default. function SHOULD be disabled by default.
3.5.6. Synchronization and Flooding Procedures 2.5.6. Synchronization and Flooding Procedures
3.5.6.1. Unicast Synchronization 2.5.6.1. Unicast Synchronization
A synchronization initiator sends a synchronization request to a A synchronization initiator opens a transport connection to a
counterpart, including a specific synchronization objective. The counterpart ASA using the address, protocol and port obtained during
counterpart responds with a Synchronization message (Section 3.8.10) discovery. It then sends a synchronization request (using M_REQ_SYN)
containing the current value of the requested synchronization to the counterpart, including a specific synchronization objective.
objective. No further messages are needed. The counterpart responds with a Synchronization message (M_SYNCH,
Section 2.8.10) containing the current value of the requested
synchronization objective. No further messages are needed and the
transport connection SHOULD be closed. A transport session failure
is treated as a synchronization failure.
If no reply message of any kind is received within a reasonable If no reply message of any kind is received within a given timeout
timeout (default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the (default GRASP_DEF_TIMEOUT milliseconds, Section 2.6), the
synchronization request MAY be repeated, with a newly generated synchronization request MAY be repeated, with a newly generated
Session ID (Section 3.7). An exponential backoff SHOULD be used for Session ID (Section 2.7). An exponential backoff SHOULD be used for
subsequent repetitions. subsequent repetitions. The details of the backoff algorithm will
depend on the use case for the objective concerned.
3.5.6.2. Flooding 2.5.6.2. Flooding
In the case just described, the message exchange is unicast and In the case just described, the message exchange is unicast and
concerns only one synchronization objective. For large groups of concerns only one synchronization objective. For large groups of
nodes requiring the same data, synchronization flooding is available. nodes requiring the same data, synchronization flooding is available.
For this, a flooding initiator MAY send an unsolicited Flood For this, a flooding initiator MAY send an unsolicited Flood
Synchronization message containing one or more Synchronization Synchronization message containing one or more Synchronization
Objective option(s), if and only if the specification of those Objective option(s), if and only if the specification of those
objectives permits it. This is sent as a multicast message to the objectives permits it. This is sent as a multicast message to the
ALL_GRASP_NEIGHBORS multicast address (Section 3.6). ALL_GRASP_NEIGHBORS multicast address (Section 2.6).
Receiving flood multicasts is a function of the GRASP core, as in the Receiving flood multicasts is a function of the GRASP core, as in the
case of discovery multicasts (Section 3.5.4.3). case of discovery multicasts (Section 2.5.4.3).
To ensure that flooding does not result in a loop, the originator of To ensure that flooding does not result in a loop, the originator of
the Flood Synchronization message MUST set the loop count in the the Flood Synchronization message MUST set the loop count in the
objectives to a suitable value (the default is GRASP_DEF_LOOPCT). objectives to a suitable value (the default is GRASP_DEF_LOOPCT).
Also, a suitable mechanism is needed to avoid excessive multicast Also, a suitable mechanism is needed to avoid excessive multicast
traffic. This mechanism MUST be defined as part of the specification traffic. This mechanism MUST be defined as part of the specification
of the synchronization objective(s) concerned. It might be a simple of the synchronization objective(s) concerned. It might be a simple
rate limit or a more complex mechanism such as the Trickle algorithm rate limit or a more complex mechanism such as the Trickle algorithm
[RFC6206]. [RFC6206].
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Link-layer Flooding is supported by GRASP by setting the loop count Link-layer Flooding is supported by GRASP by setting the loop count
to 1, and sending with a link-local source address. Floods with to 1, and sending with a link-local source address. Floods with
link-local source addresses and a loop count other than 1 are link-local source addresses and a loop count other than 1 are
invalid, and such messages MUST be discarded. invalid, and such messages MUST be discarded.
The relaying device MUST decrement the loop count within the first The relaying device MUST decrement the loop count within the first
objective, and MUST NOT relay the Flood Synchronization message if objective, and MUST NOT relay the Flood Synchronization message if
the result is zero. Also, it MUST limit the total rate at which it the result is zero. Also, it MUST limit the total rate at which it
relays Flood Synchronization messages to a reasonable value, in order relays Flood Synchronization messages to a reasonable value, in order
to mitigate possible denial of service attacks. It MUST cache the to mitigate possible denial of service attacks. For example, the
Session ID value and initiator address of each relayed Flood rate limit could be set to a small multiple of the observed rate of
Synchronization message for a time not less than twice flood messages during normal operation. The relaying device MUST
cache the Session ID value and initiator address of each relayed
Flood Synchronization message for a time not less than twice
GRASP_DEF_TIMEOUT milliseconds. To prevent loops, it MUST NOT relay GRASP_DEF_TIMEOUT milliseconds. To prevent loops, it MUST NOT relay
a Flood Synchronization message which carries a given cached Session a Flood Synchronization message which carries a given cached Session
ID and initiator address more than once. These precautions avoid ID and initiator address more than once. These precautions avoid
synchronization loops and mitigate potential overload. synchronization loops and mitigate potential overload.
Note that this mechanism is unreliable in the case of sleeping nodes, Note that this mechanism is unreliable in the case of sleeping nodes,
or new nodes that join the network, or nodes that rejoin the network or new nodes that join the network, or nodes that rejoin the network
after a fault. An ASA that initiates a flood SHOULD repeat the flood after a fault. An ASA that initiates a flood SHOULD repeat the flood
at a suitable frequency and SHOULD also act as a synchronization at a suitable frequency, which MUST be consistent with the
responder for the objective(s) concerned. Thus nodes that require an recommendations in [RFC8085] for low data-volume multicast. The ASA
objective subject to flooding can either wait for the next flood or SHOULD also act as a synchronization responder for the objective(s)
request unicast synchronization for that objective. concerned. Thus nodes that require an objective subject to flooding
can either wait for the next flood or request unicast synchronization
for that objective.
The multicast messages for synchronization flooding are subject to The multicast messages for synchronization flooding are subject to
the security rules in Section 3.5.1. In practice this means that the security rules in Section 2.5.1. In practice this means that
they MUST NOT be transmitted and MUST be ignored on receipt unless they MUST NOT be transmitted and MUST be ignored on receipt unless
there is an operational ACP or equivalent strong security in place. there is an operational ACP or equivalent strong security in place.
However, because of the security weakness of link-local multicast However, because of the security weakness of link-local multicast
(Section 5), synchronization objectives that are flooded SHOULD NOT (Section 4), synchronization objectives that are flooded SHOULD NOT
contain unencrypted private information and SHOULD be validated by contain unencrypted private information and SHOULD be validated by
the recipient ASA. the recipient ASA.
3.5.6.3. Rapid Mode (Discovery/Synchronization Linkage) 2.5.6.3. Rapid Mode (Discovery/Synchronization Linkage)
A Discovery message MAY include a Synchronization Objective option. A Discovery message MAY include a Synchronization Objective option.
In this case the Discovery message also acts as a Request In this case the Discovery message also acts as a Request
Synchronization message to indicate to the Discovery Responder that Synchronization message to indicate to the Discovery Responder that
it could directly reply to the Discovery Initiator with a it could directly reply to the Discovery Initiator with a
Synchronization message Section 3.8.10 with synchronization data for Synchronization message Section 2.8.10 with synchronization data for
rapid processing, if the discovery target supports the corresponding rapid processing, if the discovery target supports the corresponding
synchronization objective. The design implications are similar to synchronization objective. The design implications are similar to
those discussed in Section 3.5.5.1. those discussed in Section 2.5.5.1.
It is possible that a Discovery Response will arrive from a responder It is possible that a Discovery Response will arrive from a responder
that does not support rapid mode, before such a Synchronization that does not support rapid mode, before such a Synchronization
message arrives. In this case, rapid mode will not occur. message arrives. In this case, rapid mode will not occur.
This rapid mode could reduce the interactions between nodes so that a This rapid mode could reduce the interactions between nodes so that a
higher efficiency could be achieved. However, a network in which higher efficiency could be achieved. However, a network in which
some nodes support rapid mode and others do not will have complex some nodes support rapid mode and others do not will have complex
timing-dependent behaviors. Therefore, the rapid synchronization timing-dependent behaviors. Therefore, the rapid synchronization
function SHOULD be configured off by default and MAY be configured on function SHOULD be configured off by default and MAY be configured on
or off by Intent. or off by Intent.
3.6. GRASP Constants 2.6. GRASP Constants
o ALL_GRASP_NEIGHBORS o ALL_GRASP_NEIGHBORS
A link-local scope multicast address used by a GRASP-enabled A link-local scope multicast address used by a GRASP-enabled
device to discover GRASP-enabled neighbor (i.e., on-link) devices. device to discover GRASP-enabled neighbor (i.e., on-link) devices.
All devices that support GRASP are members of this multicast All devices that support GRASP are members of this multicast
group. group.
* IPv6 multicast address: TBD1 * IPv6 multicast address: TBD1
* IPv4 multicast address: TBD2 * IPv4 multicast address: TBD2
o GRASP_LISTEN_PORT (TBD3) o GRASP_LISTEN_PORT (TBD3)
A well-known UDP user port that every GRASP-enabled network device A well-known UDP user port that every GRASP-enabled network device
MUST always listen to for link-local multicasts. This user port MUST always listen to for link-local multicasts. This user port
MAY also be used to listen for TCP or UDP unicast messages in a MAY also be used to listen for TCP or UDP unicast messages in a
simple implementation of GRASP (Section 3.5.3). simple implementation of GRASP (Section 2.5.3).
o GRASP_DEF_TIMEOUT (60000 milliseconds) o GRASP_DEF_TIMEOUT (60000 milliseconds)
The default timeout used to determine that a discovery etc. has The default timeout used to determine that an operation has failed
failed to complete. to complete.
o GRASP_DEF_LOOPCT (6) o GRASP_DEF_LOOPCT (6)
The default loop count used to determine that a negotiation has The default loop count used to determine that a negotiation has
failed to complete, and to avoid looping messages. failed to complete, and to avoid looping messages.
o GRASP_DEF_MAX_SIZE (2048) o GRASP_DEF_MAX_SIZE (2048)
The default maximum message size in bytes. The default maximum message size in bytes.
3.7. Session Identifier (Session ID) 2.7. Session Identifier (Session ID)
This is an up to 32-bit opaque value used to distinguish multiple This is an up to 32-bit opaque value used to distinguish multiple
sessions between the same two devices. A new Session ID MUST be sessions between the same two devices. A new Session ID MUST be
generated by the initiator for every new Discovery, Flood generated by the initiator for every new Discovery, Flood
Synchronization or Request message. All responses and follow-up Synchronization or Request message. All responses and follow-up
messages in the same discovery, synchronization or negotiation messages in the same discovery, synchronization or negotiation
procedure MUST carry the same Session ID. procedure MUST carry the same Session ID.
The Session ID SHOULD have a very low collision rate locally. It The Session ID SHOULD have a very low collision rate locally. It
MUST be generated by a pseudo-random algorithm using a locally MUST be generated by a pseudo-random number generator (PRNG) using a
generated seed which is unlikely to be used by any other device in locally generated seed which is unlikely to be used by any other
the same network [RFC4086]. When allocating a new Session ID, GRASP device in the same network. The PRNG SHOULD be cryptographically
MUST check that the value is not already in use and SHOULD check that strong [RFC4086]. When allocating a new Session ID, GRASP MUST check
it has not been used recently, by consulting a cache of current and that the value is not already in use and SHOULD check that it has not
recent sessions. In the unlikely event of a clash, GRASP MUST been used recently, by consulting a cache of current and recent
generate a new value. sessions. In the unlikely event of a clash, GRASP MUST generate a
new value.
However, there is a finite probability that two nodes might generate However, there is a finite probability that two nodes might generate
the same Session ID value. For that reason, when a Session ID is the same Session ID value. For that reason, when a Session ID is
communicated via GRASP, the receiving node MUST tag it with the communicated via GRASP, the receiving node MUST tag it with the
initiator's IP address to allow disambiguation. In the highly initiator's IP address to allow disambiguation. In the highly
unlikely event of two peers opening sessions with the same Session ID unlikely event of two peers opening sessions with the same Session ID
value, this tag will allow the two sessions to be distinguished. value, this tag will allow the two sessions to be distinguished.
Multicast GRASP messages and their responses, which may be relayed Multicast GRASP messages and their responses, which may be relayed
between links, therefore include a field that carries the initiator's between links, therefore include a field that carries the initiator's
global IP address. global IP address.
There is a highly unlikely race condition in which two peers start There is a highly unlikely race condition in which two peers start
simultaneous negotiation sessions with each other using the same simultaneous negotiation sessions with each other using the same
Session ID value. Depending on various implementation choices, this Session ID value. Depending on various implementation choices, this
might lead to the two sessions being confused. See Section 3.8.6 for might lead to the two sessions being confused. See Section 2.8.6 for
details of how to avoid this. details of how to avoid this.
3.8. GRASP Messages 2.8. GRASP Messages
3.8.1. Message Overview 2.8.1. Message Overview
This section defines the GRASP message format and message types. This section defines the GRASP message format and message types.
Message types not listed here are reserved for future use. Message types not listed here are reserved for future use.
The messages currently defined are: The messages currently defined are:
Discovery and Discovery Response (M_DISCOVERY, M_RESPONSE). Discovery and Discovery Response (M_DISCOVERY, M_RESPONSE).
Request Negotiation, Negotiation, Confirm Waiting and Negotiation Request Negotiation, Negotiation, Confirm Waiting and Negotiation
End (M_REQ_NEG, M_NEGOTIATE, M_WAIT, M_END). End (M_REQ_NEG, M_NEGOTIATE, M_WAIT, M_END).
Request Synchronization, Synchronization, and Flood Request Synchronization, Synchronization, and Flood
Synchronization (M_REQ_SYN, M_SYNCH, M_FLOOD. Synchronization (M_REQ_SYN, M_SYNCH, M_FLOOD.
No Operation and Invalid (M_NOOP, M_INVALID). No Operation and Invalid (M_NOOP, M_INVALID).
3.8.2. GRASP Message Format 2.8.2. GRASP Message Format
GRASP messages share an identical header format and a variable format GRASP messages share an identical header format and a variable format
area for options. GRASP message headers and options are transmitted area for options. GRASP message headers and options are transmitted
in Concise Binary Object Representation (CBOR) [RFC7049]. In this in Concise Binary Object Representation (CBOR) [RFC7049]. In this
specification, they are described using CBOR data definition language specification, they are described using CBOR data definition language
(CDDL) [I-D.greevenbosch-appsawg-cbor-cddl]. Fragmentary CDDL is (CDDL) [I-D.greevenbosch-appsawg-cbor-cddl]. Fragmentary CDDL is
used to describe each item in this section. A complete and normative used to describe each item in this section. A complete and normative
CDDL specification of GRASP is given in Section 6, including CDDL specification of GRASP is given in Section 5, including
constants such as message types. constants such as message types.
Every GRASP message, except the No Operation message, carries a Every GRASP message, except the No Operation message, carries a
Session ID (Section 3.7). Options are then presented serially in the Session ID (Section 2.7). Options are then presented serially in the
options field. options field.
In fragmentary CDDL, every GRASP message follows the pattern: In fragmentary CDDL, every GRASP message follows the pattern:
grasp-message = (message .within message-structure) / noop-message grasp-message = (message .within message-structure) / noop-message
message-structure = [MESSAGE_TYPE, session-id, ?initiator, message-structure = [MESSAGE_TYPE, session-id, ?initiator,
*grasp-option] *grasp-option]
MESSAGE_TYPE = 1..255 MESSAGE_TYPE = 1..255
session-id = 0..4294967295 ;up to 32 bits session-id = 0..4294967295 ;up to 32 bits
grasp-option = any grasp-option = any
The MESSAGE_TYPE indicates the type of the message and thus defines The MESSAGE_TYPE indicates the type of the message and thus defines
the expected options. Any options received that are not consistent the expected options. Any options received that are not consistent
with the MESSAGE_TYPE SHOULD be silently discarded. with the MESSAGE_TYPE SHOULD be silently discarded.
The No Operation (noop) message is described in Section 3.8.13. The No Operation (noop) message is described in Section 2.8.13.
The various MESSAGE_TYPE values are defined in Section 6. The various MESSAGE_TYPE values are defined in Section 5.
All other message elements are described below and formally defined All other message elements are described below and formally defined
in Section 6. in Section 5.
If an unrecognized MESSAGE_TYPE is received in a unicast message, an If an unrecognized MESSAGE_TYPE is received in a unicast message, an
Invalid message (Section 3.8.12) MAY be returned. Otherwise the Invalid message (Section 2.8.12) MAY be returned. Otherwise the
message MAY be logged and MUST be discarded. If an unrecognized message MAY be logged and MUST be discarded. If an unrecognized
MESSAGE_TYPE is received in a multicast message, it MAY be logged and MESSAGE_TYPE is received in a multicast message, it MAY be logged and
MUST be silently discarded. MUST be silently discarded.
3.8.3. Message Size 2.8.3. Message Size
GRASP nodes MUST be able to receive unicast messages of at least GRASP nodes MUST be able to receive unicast messages of at least
GRASP_DEF_MAX_SIZE bytes. GRASP nodes MUST NOT send unicast messages GRASP_DEF_MAX_SIZE bytes. GRASP nodes MUST NOT send unicast messages
longer than GRASP_DEF_MAX_SIZE bytes unless a longer size is longer than GRASP_DEF_MAX_SIZE bytes unless a longer size is
explicitly allowed for the objective concerned. For example, GRASP explicitly allowed for the objective concerned. For example, GRASP
negotiation itself could be used to agree on a longer message size. negotiation itself could be used to agree on a longer message size.
The message parser used by GRASP should be configured to know about The message parser used by GRASP should be configured to know about
the GRASP_DEF_MAX_SIZE, or any larger negotiated message size, so the GRASP_DEF_MAX_SIZE, or any larger negotiated message size, so
that it may defend against overly long messages. that it may defend against overly long messages.
The maximum size of multicast messages (M_DISCOVERY and M_FLOOD) The maximum size of multicast messages (M_DISCOVERY and M_FLOOD)
depends on the link layer technology or link adaptation layer in use. depends on the link layer technology or link adaptation layer in use.
3.8.4. Discovery Message 2.8.4. Discovery Message
In fragmentary CDDL, a Discovery message follows the pattern: In fragmentary CDDL, a Discovery message follows the pattern:
discovery-message = [M_DISCOVERY, session-id, initiator, objective] discovery-message = [M_DISCOVERY, session-id, initiator, objective]
A discovery initiator sends a Discovery message to initiate a A discovery initiator sends a Discovery message to initiate a
discovery process for a particular objective option. discovery process for a particular objective option.
The discovery initiator sends all Discovery messages via UDP to port The discovery initiator sends all Discovery messages via UDP to port
GRASP_LISTEN_PORT at the link-local ALL_GRASP_NEIGHBORS multicast GRASP_LISTEN_PORT at the link-local ALL_GRASP_NEIGHBORS multicast
address on each link-layer interface in use by GRASP. It then address on each link-layer interface in use by GRASP. It then
listens for unicast TCP responses on a given port, and stores the listens for unicast TCP responses on a given port, and stores the
discovery results (including responding discovery objectives and discovery results (including responding discovery objectives and
corresponding unicast locators). corresponding unicast locators).
The listening port used for TCP MUST be the same port as used for The listening port used for TCP MUST be the same port as used for
sending the Discovery UDP multicast, on a given interface. In a low- sending the Discovery UDP multicast, on a given interface. In an
end implementation this MAY be GRASP_LISTEN_PORT. In a more complex implementation with a single GRASP instance in a node this MAY be
implementation, the GRASP discovery mechanism will find, for each GRASP_LISTEN_PORT. To support multiple instances in the same node,
interface, a dynamic port that it can bind to for both UDP and TCP the GRASP discovery mechanism in each instance needs to find, for
before initiating any discovery. each interface, a dynamic port that it can bind to for both sending
UDP link-local multicast and listening for TCP, before initiating any
discovery.
The 'initiator' field in the message is a globally unique IP address The 'initiator' field in the message is a globally unique IP address
of the initiator, for the sole purpose of disambiguating the Session of the initiator, for the sole purpose of disambiguating the Session
ID in other nodes. If for some reason the initiator does not have a ID in other nodes. If for some reason the initiator does not have a
globally unique IP address, it MUST use a link-local address for this globally unique IP address, it MUST use a link-local address for this
purpose that is highly likely to be unique, for example using purpose that is highly likely to be unique, for example using
[RFC7217].
[RFC7217]. Determination of a node's globally unique IP address is
implementation-dependent.
A Discovery message MUST include exactly one of the following: A Discovery message MUST include exactly one of the following:
o a discovery objective option (Section 3.10.1). Its loop count o a discovery objective option (Section 2.10.1). Its loop count
MUST be set to a suitable value to prevent discovery loops MUST be set to a suitable value to prevent discovery loops
(default value is GRASP_DEF_LOOPCT). If the discovery initiator (default value is GRASP_DEF_LOOPCT). If the discovery initiator
requires only on-link responses, the loop count MUST be set to 1. requires only on-link responses, the loop count MUST be set to 1.
o a negotiation objective option (Section 3.10.1). This is used o a negotiation objective option (Section 2.10.1). This is used
both for the purpose of discovery and to indicate to the discovery both for the purpose of discovery and to indicate to the discovery
target that it MAY directly reply to the discovery initiatior with target that it MAY directly reply to the discovery initiatior with
a Negotiation message for rapid processing, if it could act as the a Negotiation message for rapid processing, if it could act as the
corresponding negotiation counterpart. The sender of such a corresponding negotiation counterpart. The sender of such a
Discovery message MUST initialize a negotiation timer and loop Discovery message MUST initialize a negotiation timer and loop
count in the same way as a Request Negotiation message count in the same way as a Request Negotiation message
(Section 3.8.6). (Section 2.8.6).
o a synchronization objective option (Section 3.10.1). This is used o a synchronization objective option (Section 2.10.1). This is used
both for the purpose of discovery and to indicate to the discovery both for the purpose of discovery and to indicate to the discovery
target that it MAY directly reply to the discovery initiator with target that it MAY directly reply to the discovery initiator with
a Synchronization message for rapid processing, if it could act as a Synchronization message for rapid processing, if it could act as
the corresponding synchronization counterpart. Its loop count the corresponding synchronization counterpart. Its loop count
MUST be set to a suitable value to prevent discovery loops MUST be set to a suitable value to prevent discovery loops
(default value is GRASP_DEF_LOOPCT). (default value is GRASP_DEF_LOOPCT).
As mentioned in Section 3.5.4.2, a Discovery message MAY be sent As mentioned in Section 2.5.4.2, a Discovery message MAY be sent
unicast to a peer node, which SHOULD then proceed exactly as if the unicast to a peer node, which SHOULD then proceed exactly as if the
message had been multicast. message had been multicast.
3.8.5. Discovery Response Message 2.8.5. Discovery Response Message
In fragmentary CDDL, a Discovery Response message follows the In fragmentary CDDL, a Discovery Response message follows the
pattern: pattern:
response-message = [M_RESPONSE, session-id, initiator, ttl, response-message = [M_RESPONSE, session-id, initiator, ttl,
(+locator-option // divert-option), ?objective)] (+locator-option // divert-option), ?objective)]
ttl = 0..4294967295 ; in milliseconds ttl = 0..4294967295 ; in milliseconds
A node which receives a Discovery message SHOULD send a Discovery A node which receives a Discovery message SHOULD send a Discovery
Response message if and only if it can respond to the discovery. Response message if and only if it can respond to the discovery.
It MUST contain the same Session ID and initiator as the Discovery It MUST contain the same Session ID and initiator as the Discovery
message. message.
It MUST contain a time-to-live (ttl) for the validity of the It MUST contain a time-to-live (ttl) for the validity of the
response, given as a positive integer value in milliseconds. Zero response, given as a positive integer value in milliseconds. Zero
is treated as the default value GRASP_DEF_TIMEOUT (Section 3.6). implies a value significantly greater than GRASP_DEF_TIMEOUT
milliseconds (Section 2.6). A suggested value is ten times that
amount.
It MAY include a copy of the discovery objective from the It MAY include a copy of the discovery objective from the
Discovery message. Discovery message.
It is sent to the sender of the Discovery message via TCP at the port It is sent to the sender of the Discovery message via TCP at the port
used to send the Discovery message (as explained in Section 3.8.4). used to send the Discovery message (as explained in Section 2.8.4).
In the case of a relayed Discovery message, the Discovery Response is In the case of a relayed Discovery message, the Discovery Response is
thus sent to the relay, not the original initiator. thus sent to the relay, not the original initiator.
In all cases, the transport session SHOULD be closed after sending
the Discovery Response. A transport session failure is treated as no
response.
If the responding node supports the discovery objective of the If the responding node supports the discovery objective of the
discovery, it MUST include at least one kind of locator option discovery, it MUST include at least one kind of locator option
(Section 3.9.5) to indicate its own location. A sequence of multiple (Section 2.9.5) to indicate its own location. A sequence of multiple
kinds of locator options (e.g. IP address option and FQDN option) is kinds of locator options (e.g. IP address option and FQDN option) is
also valid. also valid.
If the responding node itself does not support the discovery If the responding node itself does not support the discovery
objective, but it knows the locator of the discovery objective, then objective, but it knows the locator of the discovery objective, then
it SHOULD respond to the discovery message with a divert option it SHOULD respond to the discovery message with a divert option
(Section 3.9.2) embedding a locator option or a combination of (Section 2.9.2) embedding a locator option or a combination of
multiple kinds of locator options which indicate the locator(s) of multiple kinds of locator options which indicate the locator(s) of
the discovery objective. the discovery objective.
More details on the processing of Discovery Responses are given in More details on the processing of Discovery Responses are given in
Section 3.5.4. Section 2.5.4.
3.8.6. Request Messages 2.8.6. Request Messages
In fragmentary CDDL, Request Negotiation and Request Synchronization In fragmentary CDDL, Request Negotiation and Request Synchronization
messages follow the patterns: messages follow the patterns:
request-negotiation-message = [M_REQ_NEG, session-id, objective] request-negotiation-message = [M_REQ_NEG, session-id, objective]
request-synchronization-message = [M_REQ_SYN, session-id, objective] request-synchronization-message = [M_REQ_SYN, session-id, objective]
A negotiation or synchronization requesting node sends the A negotiation or synchronization requesting node sends the
appropriate Request message to the unicast address of the negotiation appropriate Request message to the unicast address of the negotiation
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port numbers (selected from the discovery result). If the discovery port numbers (selected from the discovery result). If the discovery
result is an FQDN, it will be resolved first. result is an FQDN, it will be resolved first.
A Request message MUST include the relevant objective option. In the A Request message MUST include the relevant objective option. In the
case of Request Negotiation, the objective option MUST include the case of Request Negotiation, the objective option MUST include the
requested value. requested value.
When an initiator sends a Request Negotiation message, it MUST When an initiator sends a Request Negotiation message, it MUST
initialize a negotiation timer for the new negotiation thread. The initialize a negotiation timer for the new negotiation thread. The
default is GRASP_DEF_TIMEOUT milliseconds. Unless this timeout is default is GRASP_DEF_TIMEOUT milliseconds. Unless this timeout is
modified by a Confirm Waiting message (Section 3.8.9), the initiator modified by a Confirm Waiting message (Section 2.8.9), the initiator
will consider that the negotiation has failed when the timer expires. will consider that the negotiation has failed when the timer expires.
Similarly, when an initiator sends a Request Synchronization, it Similarly, when an initiator sends a Request Synchronization, it
SHOULD initialize a synchronization timer. The default is SHOULD initialize a synchronization timer. The default is
GRASP_DEF_TIMEOUT milliseconds. The initiator will consider that GRASP_DEF_TIMEOUT milliseconds. The initiator will consider that
synchronization has failed if there is no response before the timer synchronization has failed if there is no response before the timer
expires. expires.
When an initiator sends a Request message, it MUST initialize the When an initiator sends a Request message, it MUST initialize the
loop count of the objective option with a value defined in the loop count of the objective option with a value defined in the
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GRASP_DEF_LOOPCT. GRASP_DEF_LOOPCT.
If a node receives a Request message for an objective for which no If a node receives a Request message for an objective for which no
ASA is currently listening, it MUST immediately close the relevant ASA is currently listening, it MUST immediately close the relevant
socket to indicate this to the initiator. This is to avoid socket to indicate this to the initiator. This is to avoid
unnecessary timeouts if, for example, an ASA exits prematurely but unnecessary timeouts if, for example, an ASA exits prematurely but
the GRASP core is listening on its behalf. the GRASP core is listening on its behalf.
To avoid the highly unlikely race condition in which two nodes To avoid the highly unlikely race condition in which two nodes
simultaneously request sessions with each other using the same simultaneously request sessions with each other using the same
Session ID (Section 3.7), when a node receives a Request message, it Session ID (Section 2.7), when a node receives a Request message, it
MUST verify that the received Session ID is not already locally MUST verify that the received Session ID is not already locally
active. In case of a clash, it MUST discard the Request message, in active. In case of a clash, it MUST discard the Request message, in
which case the initiator will detect a timeout. which case the initiator will detect a timeout.
3.8.7. Negotiation Message 2.8.7. Negotiation Message
In fragmentary CDDL, a Negotiation message follows the pattern: In fragmentary CDDL, a Negotiation message follows the pattern:
negotiate-message = [M_NEGOTIATE, session-id, objective] negotiate-message = [M_NEGOTIATE, session-id, objective]
A negotiation counterpart sends a Negotiation message in response to A negotiation counterpart sends a Negotiation message in response to
a Request Negotiation message, a Negotiation message, or a Discovery a Request Negotiation message, a Negotiation message, or a Discovery
message in Rapid Mode. A negotiation process MAY include multiple message in Rapid Mode. A negotiation process MAY include multiple
steps. steps.
The Negotiation message MUST include the relevant Negotiation The Negotiation message MUST include the relevant Negotiation
Objective option, with its value updated according to progress in the Objective option, with its value updated according to progress in the
negotiation. The sender MUST decrement the loop count by 1. If the negotiation. The sender MUST decrement the loop count by 1. If the
loop count becomes zero the message MUST NOT be sent. In this case loop count becomes zero the message MUST NOT be sent. In this case
the negotiation session has failed and will time out. the negotiation session has failed and will time out.
3.8.8. Negotiation End Message 2.8.8. Negotiation End Message
In fragmentary CDDL, a Negotiation End message follows the pattern: In fragmentary CDDL, a Negotiation End message follows the pattern:
end-message = [M_END, session-id, accept-option / decline-option] end-message = [M_END, session-id, accept-option / decline-option]
A negotiation counterpart sends an Negotiation End message to close A negotiation counterpart sends an Negotiation End message to close
the negotiation. It MUST contain either an accept or a decline the negotiation. It MUST contain either an accept or a decline
option, defined in Section 3.9.3 and Section 3.9.4. It could be sent option, defined in Section 2.9.3 and Section 2.9.4. It could be sent
either by the requesting node or the responding node. either by the requesting node or the responding node.
3.8.9. Confirm Waiting Message 2.8.9. Confirm Waiting Message
In fragmentary CDDL, a Confirm Waiting message follows the pattern: In fragmentary CDDL, a Confirm Waiting message follows the pattern:
wait-message = [M_WAIT, session-id, waiting-time] wait-message = [M_WAIT, session-id, waiting-time]
waiting-time = 0..4294967295 ; in milliseconds waiting-time = 0..4294967295 ; in milliseconds
A responding node sends a Confirm Waiting message to ask the A responding node sends a Confirm Waiting message to ask the
requesting node to wait for a further negotiation response. It might requesting node to wait for a further negotiation response. It might
be that the local process needs more time or that the negotiation be that the local process needs more time or that the negotiation
depends on another triggered negotiation. This message MUST NOT depends on another triggered negotiation. This message MUST NOT
include any other options. When received, the waiting time value include any other options. When received, the waiting time value
overwrites and restarts the current negotiation timer overwrites and restarts the current negotiation timer
(Section 3.8.6). (Section 2.8.6).
The responding node SHOULD send a Negotiation, Negotiation End or The responding node SHOULD send a Negotiation, Negotiation End or
another Confirm Waiting message before the negotiation timer expires. another Confirm Waiting message before the negotiation timer expires.
If not, the initiator MUST abandon or restart the negotiation If not, when the initiator's timer expires, the initiator MUST treat
procedure, to avoid an indefinite wait. the negotiation procedure as failed.
3.8.10. Synchronization Message 2.8.10. Synchronization Message
In fragmentary CDDL, a Synchronization message follows the pattern: In fragmentary CDDL, a Synchronization message follows the pattern:
synch-message = [M_SYNCH, session-id, objective] synch-message = [M_SYNCH, session-id, objective]
A node which receives a Request Synchronization, or a Discovery A node which receives a Request Synchronization, or a Discovery
message in Rapid Mode, sends back a unicast Synchronization message message in Rapid Mode, sends back a unicast Synchronization message
with the synchronization data, in the form of a GRASP Option for the with the synchronization data, in the form of a GRASP Option for the
specific synchronization objective present in the Request specific synchronization objective present in the Request
Synchronization. Synchronization.
3.8.11. Flood Synchronization Message 2.8.11. Flood Synchronization Message
In fragmentary CDDL, a Flood Synchronization message follows the In fragmentary CDDL, a Flood Synchronization message follows the
pattern: pattern:
flood-message = [M_FLOOD, session-id, initiator, ttl, flood-message = [M_FLOOD, session-id, initiator, ttl,
+[objective, (locator-option / [])]] +[objective, (locator-option / [])]]
ttl = 0..4294967295 ; in milliseconds ttl = 0..4294967295 ; in milliseconds
A node MAY initiate flooding by sending an unsolicited Flood A node MAY initiate flooding by sending an unsolicited Flood
Synchronization Message with synchronization data. This MAY be sent Synchronization Message with synchronization data. This MAY be sent
to port GRASP_LISTEN_PORT at the link-local ALL_GRASP_NEIGHBORS to port GRASP_LISTEN_PORT at the link-local ALL_GRASP_NEIGHBORS
multicast address, in accordance with the rules in Section 3.5.6. multicast address, in accordance with the rules in Section 2.5.6.
The initiator address is provided, as described for Discovery The initiator address is provided, as described for Discovery
messages (Section 3.8.4), only to disambiguate the Session ID. messages (Section 2.8.4), only to disambiguate the Session ID.
The message MUST contain a time-to-live (ttl) for the validity of The message MUST contain a time-to-live (ttl) for the validity of
the contents, given as a positive integer value in milliseconds. the contents, given as a positive integer value in milliseconds.
There is no default; zero indicates an indefinite lifetime. There is no default; zero indicates an indefinite lifetime.
The synchronization data are in the form of GRASP Option(s) for The synchronization data are in the form of GRASP Option(s) for
specific synchronization objective(s). The loop count(s) MUST be specific synchronization objective(s). The loop count(s) MUST be
set to a suitable value to prevent flood loops (default value is set to a suitable value to prevent flood loops (default value is
GRASP_DEF_LOOPCT). GRASP_DEF_LOOPCT).
Each objective option MAY be followed by a locator option Each objective option MAY be followed by a locator option
associated with the flooded objective. In its absence, an empty associated with the flooded objective. In its absence, an empty
option MUST be included to indicate a null locator. option MUST be included to indicate a null locator.
A node that receives a Flood Synchronization message MUST cache the A node that receives a Flood Synchronization message MUST cache the
received objectives for use by local ASAs. Each cached objective received objectives for use by local ASAs. Each cached objective
MUST be tagged with the locator option sent with it, or with a null MUST be tagged with the locator option sent with it, or with a null
tag if an empty locator option was sent. If a subsequent Flood tag if an empty locator option was sent. If a subsequent Flood
Synchronization message carrying the same objective arrives with the Synchronization message carrying an objective with same name and the
same tag, the corresponding cached copy of the objective MUST be same tag, the corresponding cached copy of the objective MUST be
overwritten. If a subsequent Flood Synchronization message carrying overwritten. If a subsequent Flood Synchronization message carrying
the same objective arrives with a different tag, a new cached entry an objective with same name arrives with a different tag, a new
MUST be created. cached entry MUST be created.
Note: the purpose of this mechanism is to allow the recipient of Note: the purpose of this mechanism is to allow the recipient of
flooded values to distinguish between different senders of the same flooded values to distinguish between different senders of the same
objective, and if necessary communicate with them using the locator, objective, and if necessary communicate with them using the locator,
protocol and port included in the locator option. Many objectives protocol and port included in the locator option. Many objectives
will not need this mechanism, so they will be flooded with a null will not need this mechanism, so they will be flooded with a null
locator. locator.
Cached entries MUST be ignored or deleted after their lifetime Cached entries MUST be ignored or deleted after their lifetime
expires. expires.
3.8.12. Invalid Message 2.8.12. Invalid Message
In fragmentary CDDL, an Invalid message follows the pattern: In fragmentary CDDL, an Invalid message follows the pattern:
invalid-message = [M_INVALID, session-id, ?any] invalid-message = [M_INVALID, session-id, ?any]
This message MAY be sent by an implementation in response to an This message MAY be sent by an implementation in response to an
incoming unicast message that it considers invalid. The session-id incoming unicast message that it considers invalid. The session-id
MUST be copied from the incoming message. The content SHOULD be MUST be copied from the incoming message. The content SHOULD be
diagnostic information such as a partial copy of the invalid message. diagnostic information such as a partial copy of the invalid message
An M_INVALID message MAY be silently ignored by a recipient. up to the maximum message size. An M_INVALID message MAY be silently
However, it could be used in support of extensibility, since it ignored by a recipient. However, it could be used in support of
indicates that the remote node does not support a new or obsolete extensibility, since it indicates that the remote node does not
message or option. support a new or obsolete message or option.
An M_INVALID message MUST NOT be sent in response to an M_INVALID An M_INVALID message MUST NOT be sent in response to an M_INVALID
message. message.
3.8.13. No Operation Message 2.8.13. No Operation Message
In fragmentary CDDL, a No Operation message follows the pattern: In fragmentary CDDL, a No Operation message follows the pattern:
noop-message = [M_NOOP] noop-message = [M_NOOP]
This message MAY be sent by an implementation that for practical This message MAY be sent by an implementation that for practical
reasons needs to initialize a socket. It MUST be silently ignored by reasons needs to initialize a socket. It MUST be silently ignored by
a recipient. a recipient.
3.9. GRASP Options 2.9. GRASP Options
This section defines the GRASP options for the negotiation and This section defines the GRASP options for the negotiation and
synchronization protocol signaling. Additional options may be synchronization protocol signaling. Additional options may be
defined in the future. defined in the future.
3.9.1. Format of GRASP Options 2.9.1. Format of GRASP Options
GRASP options are CBOR objects that MUST start with an unsigned GRASP options are CBOR objects that MUST start with an unsigned
integer identifying the specific option type carried in this option. integer identifying the specific option type carried in this option.
These option types are formally defined in Section 6. Apart from These option types are formally defined in Section 5. Apart from
that the only format requirement is that each option MUST be a well- that the only format requirement is that each option MUST be a well-
formed CBOR object. In general a CBOR array format is RECOMMENDED to formed CBOR object. In general a CBOR array format is RECOMMENDED to
limit overhead. limit overhead.
GRASP options may be defined to include encapsulated GRASP options. GRASP options may be defined to include encapsulated GRASP options.
3.9.2. Divert Option 2.9.2. Divert Option
The Divert option is used to redirect a GRASP request to another The Divert option is used to redirect a GRASP request to another
node, which may be more appropriate for the intended negotiation or node, which may be more appropriate for the intended negotiation or
synchronization. It may redirect to an entity that is known as a synchronization. It may redirect to an entity that is known as a
specific negotiation or synchronization counterpart (on-link or off- specific negotiation or synchronization counterpart (on-link or off-
link) or a default gateway. The divert option MUST only be link) or a default gateway. The divert option MUST only be
encapsulated in Discovery Response messages. If found elsewhere, it encapsulated in Discovery Response messages. If found elsewhere, it
SHOULD be silently ignored. SHOULD be silently ignored.
A discovery initiator MAY ignore a Divert option if it only requires A discovery initiator MAY ignore a Divert option if it only requires
direct discovery responses. direct discovery responses.
In fragmentary CDDL, the Divert option follows the pattern: In fragmentary CDDL, the Divert option follows the pattern:
divert-option = [O_DIVERT, +locator-option] divert-option = [O_DIVERT, +locator-option]
The embedded Locator Option(s) (Section 3.9.5) point to diverted The embedded Locator Option(s) (Section 2.9.5) point to diverted
destination target(s) in response to a Discovery message. destination target(s) in response to a Discovery message.
3.9.3. Accept Option 2.9.3. Accept Option
The accept option is used to indicate to the negotiation counterpart The accept option is used to indicate to the negotiation counterpart
that the proposed negotiation content is accepted. that the proposed negotiation content is accepted.
The accept option MUST only be encapsulated in Negotiation End The accept option MUST only be encapsulated in Negotiation End
messages. If found elsewhere, it SHOULD be silently ignored. messages. If found elsewhere, it SHOULD be silently ignored.
In fragmentary CDDL, the Accept option follows the pattern: In fragmentary CDDL, the Accept option follows the pattern:
accept-option = [O_ACCEPT] accept-option = [O_ACCEPT]
3.9.4. Decline Option 2.9.4. Decline Option
The decline option is used to indicate to the negotiation counterpart The decline option is used to indicate to the negotiation counterpart
the proposed negotiation content is declined and end the negotiation the proposed negotiation content is declined and end the negotiation
process. process.
The decline option MUST only be encapsulated in Negotiation End The decline option MUST only be encapsulated in Negotiation End
messages. If found elsewhere, it SHOULD be silently ignored. messages. If found elsewhere, it SHOULD be silently ignored.
In fragmentary CDDL, the Decline option follows the pattern: In fragmentary CDDL, the Decline option follows the pattern:
decline-option = [O_DECLINE, ?reason] decline-option = [O_DECLINE, ?reason]
reason = text ;optional error message reason = text ;optional UTF-8 error message
Note: there might be scenarios where an ASA wants to decline the Note: there might be scenarios where an ASA wants to decline the
proposed value and restart the negotiation process. In this case it proposed value and restart the negotiation process. In this case it
is an implementation choice whether to send a Decline option or to is an implementation choice whether to send a Decline option or to
continue with a Negotiate message, with an objective option that continue with a Negotiate message, with an objective option that
contains a null value, or one that contains a new value that might contains a null value, or one that contains a new value that might
achieve convergence. achieve convergence.
3.9.5. Locator Options 2.9.5. Locator Options
These locator options are used to present reachability information These locator options are used to present reachability information
for an ASA, a device or an interface. They are Locator IPv6 Address for an ASA, a device or an interface. They are Locator IPv6 Address
Option, Locator IPv4 Address Option, Locator FQDN (Fully Qualified Option, Locator IPv4 Address Option, Locator FQDN (Fully Qualified
Domain Name) Option and URI (Uniform Resource Identifier) Option. Domain Name) Option and URI (Uniform Resource Identifier) Option.
Since ASAs will normally run as independent user programs, locator Since ASAs will normally run as independent user programs, locator
options need to indicate the network layer locator plus the transport options need to indicate the network layer locator plus the transport
protocol and port number for reaching the target. For this reason, protocol and port number for reaching the target. For this reason,
the Locator Options for IP addresses and FQDNs include this the Locator Options for IP addresses and FQDNs include this
information explicitly. In the case of the URI Option, this information explicitly. In the case of the URI Option, this
information can be encoded in the URI itself. information can be encoded in the URI itself.
Note: It is assumed that all locators are in scope throughout the Note: It is assumed that all locators used in locator options are in
GRASP domain. As stated in Section 3.2, GRASP is not intended to scope throughout the GRASP domain. As stated in Section 2.2, GRASP
work across disjoint addressing or naming realms. is not intended to work across disjoint addressing or naming realms.
3.9.5.1. Locator IPv6 address option 2.9.5.1. Locator IPv6 address option
In fragmentary CDDL, the IPv6 address option follows the pattern: In fragmentary CDDL, the IPv6 address option follows the pattern:
ipv6-locator-option = [O_IPv6_LOCATOR, ipv6-address, ipv6-locator-option = [O_IPv6_LOCATOR, ipv6-address,
transport-proto, port-number] transport-proto, port-number]
ipv6-address = bytes .size 16 ipv6-address = bytes .size 16
transport-proto = IPPROTO_TCP / IPPROTO_UDP transport-proto = IPPROTO_TCP / IPPROTO_UDP
IPPROTO_TCP = 6 IPPROTO_TCP = 6
IPPROTO_UDP = 17 IPPROTO_UDP = 17
port-number = 0..65535 port-number = 0..65535
The content of this option is a binary IPv6 address followed by the The content of this option is a binary IPv6 address followed by the
protocol number and port number to be used. protocol number and port number to be used.
Note 1: The IPv6 address MUST normally have global scope. However, Note 1: The IPv6 address MUST normally have global scope. However,
during initialization, a link-local address MAY be used for specific during initialization, a link-local address MAY be used for specific
objectives only (Section 3.5.2). In this case the corresponding objectives only (Section 2.5.2). In this case the corresponding
Discovery Response message MUST be sent via the interface to which Discovery Response message MUST be sent via the interface to which
the link-local address applies. the link-local address applies.
Note 2: A link-local IPv6 address MUST NOT be used when this option Note 2: A link-local IPv6 address MUST NOT be used when this option
is included in a Divert option. is included in a Divert option.
3.9.5.2. Locator IPv4 address option Note 3: The IPPROTO values are taken from the existing IANA Protocol
Numbers registry in order to specify TCP or UDP. If GRASP requires
future values that are not in that registry, a new registry for
values outside the range 0..255 will be needed.
2.9.5.2. Locator IPv4 address option
In fragmentary CDDL, the IPv4 address option follows the pattern: In fragmentary CDDL, the IPv4 address option follows the pattern:
ipv4-locator-option = [O_IPv4_LOCATOR, ipv4-address, ipv4-locator-option = [O_IPv4_LOCATOR, ipv4-address,
transport-proto, port-number] transport-proto, port-number]
ipv4-address = bytes .size 4 ipv4-address = bytes .size 4
The content of this option is a binary IPv4 address followed by the The content of this option is a binary IPv4 address followed by the
protocol number and port number to be used. protocol number and port number to be used.
Note: If an operator has internal network address translation for Note: If an operator has internal network address translation for
IPv4, this option MUST NOT be used within the Divert option. IPv4, this option MUST NOT be used within the Divert option.
3.9.5.3. Locator FQDN option 2.9.5.3. Locator FQDN option
In fragmentary CDDL, the FQDN option follows the pattern: In fragmentary CDDL, the FQDN option follows the pattern:
fqdn-locator-option = [O_FQDN_LOCATOR, text, fqdn-locator-option = [O_FQDN_LOCATOR, text,
transport-proto, port-number] transport-proto, port-number]
The content of this option is the Fully Qualified Domain Name of the The content of this option is the Fully Qualified Domain Name of the
target followed by the protocol number and port number to be used. target followed by the protocol number and port number to be used.
Note 1: Any FQDN which might not be valid throughout the network in Note 1: Any FQDN which might not be valid throughout the network in
question, such as a Multicast DNS name [RFC6762], MUST NOT be used question, such as a Multicast DNS name [RFC6762], MUST NOT be used
when this option is used within the Divert option. when this option is used within the Divert option.
Note 2: Normal GRASP operations are not expected to use this option. Note 2: Normal GRASP operations are not expected to use this option.
It is intended for special purposes such as discovering external It is intended for special purposes such as discovering external
services. services.
3.9.5.4. Locator URI option 2.9.5.4. Locator URI option
In fragmentary CDDL, the URI option follows the pattern: In fragmentary CDDL, the URI option follows the pattern:
uri-locator = [O_URI_LOCATOR, text] uri-locator = [O_URI_LOCATOR, text,
transport-proto / null, port-number / null]
The content of this option is the Uniform Resource Identifier of the The content of this option is the Uniform Resource Identifier of the
target [RFC3986]. target followed by the protocol number and port number to be used (or
by null values if not required) [RFC3986].
Note 1: Any URI which might not be valid throughout the network in Note 1: Any URI which might not be valid throughout the network in
question, such as one based on a Multicast DNS name [RFC6762], MUST question, such as one based on a Multicast DNS name [RFC6762], MUST
NOT be used when this option is used within the Divert option. NOT be used when this option is used within the Divert option.
Note 2: Normal GRASP operations are not expected to use this option. Note 2: Normal GRASP operations are not expected to use this option.
It is intended for special purposes such as discovering external It is intended for special purposes such as discovering external
services. Therefore its use is not further described in this services. Therefore its use is not further described in this
specification. specification.
3.10. Objective Options 2.10. Objective Options
3.10.1. Format of Objective Options 2.10.1. Format of Objective Options
An objective option is used to identify objectives for the purposes An objective option is used to identify objectives for the purposes
of discovery, negotiation or synchronization. All objectives MUST be of discovery, negotiation or synchronization. All objectives MUST be
in the following format, described in fragmentary CDDL: in the following format, described in fragmentary CDDL:
objective = [objective-name, objective-flags, loop-count, ?any] objective = [objective-name, objective-flags, loop-count, ?objective-value]
objective-name = text objective-name = text
loop-count = 0..255 objective-value = any
loop-count = 0..255
All objectives are identified by a unique name which is a UTF-8 All objectives are identified by a unique name which is a UTF-8
string, to be compared byte by byte. string [RFC3629], to be compared byte by byte.
The names of generic objectives MUST NOT include a colon (":") and The names of generic objectives MUST NOT include a colon (":") and
MUST be registered with IANA (Section 7). MUST be registered with IANA (Section 6).
The names of privately defined objectives MUST include at least one The names of privately defined objectives MUST include at least one
colon (":"). The string preceding the last colon in the name MUST be colon (":"). The string preceding the last colon in the name MUST be
globally unique and in some way identify the entity or person globally unique and in some way identify the entity or person
defining the objective. The following three methods MAY be used to defining the objective. The following three methods MAY be used to
create such a globally unique string: create such a globally unique string:
1. The unique string is a decimal number representing a registered 1. The unique string is a decimal number representing a registered
32 bit Private Enterprise Number (PEN) [I-D.liang-iana-pen] that 32 bit Private Enterprise Number (PEN) [I-D.liang-iana-pen] that
uniquely identifies the enterprise defining the objective. uniquely identifies the enterprise defining the objective.
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3. The unique string is an email address that uniquely identifies 3. The unique string is an email address that uniquely identifies
the entity or person defining the objective. the entity or person defining the objective.
The GRASP protocol treats the objective name as an opaque string. The GRASP protocol treats the objective name as an opaque string.
For example, "EX1", "411:EX1", "example.com:EX1", "example.org:EX1 For example, "EX1", "411:EX1", "example.com:EX1", "example.org:EX1
and "user@example.org:EX1" would be five different objectives. and "user@example.org:EX1" would be five different objectives.
The 'objective-flags' field is described below. The 'objective-flags' field is described below.
The 'loop-count' field is used for terminating negotiation as The 'loop-count' field is used for terminating negotiation as
described in Section 3.8.7. It is also used for terminating described in Section 2.8.7. It is also used for terminating
discovery as described in Section 3.5.4, and for terminating flooding discovery as described in Section 2.5.4, and for terminating flooding
as described in Section 3.5.6.2. It is placed in the objective as described in Section 2.5.6.2. It is placed in the objective
rather than in the GRASP message format because, as far as the ASA is rather than in the GRASP message format because, as far as the ASA is
concerned, it is a property of the objective itself. concerned, it is a property of the objective itself.
The 'any' field is to express the actual value of a negotiation or The 'objective-value' field is to express the actual value of a
synchronization objective. Its format is defined in the negotiation or synchronization objective. Its format is defined in
specification of the objective and may be a simple value or a data the specification of the objective and may be a simple value or a
structure of any kind. It is optional because it is optional in a data structure of any kind, as long as it can be represented in CBOR.
Discovery or Discovery Response message. It is optional because it is optional in a Discovery or Discovery
Response message.
3.10.2. Objective flags 2.10.2. Objective flags
An objective may be relevant for discovery only, for discovery and An objective may be relevant for discovery only, for discovery and
negotiation, or for discovery and synchronization. This is expressed negotiation, or for discovery and synchronization. This is expressed
in the objective by logical flag bits: in the objective by logical flag bits:
objective-flags = uint .bits objective-flag objective-flags = uint .bits objective-flag
objective-flag = &( objective-flag = &(
F_DISC: 0 ; valid for discovery F_DISC: 0 ; valid for discovery
F_NEG: 1 ; valid for negotiation F_NEG: 1 ; valid for negotiation
F_SYNCH: 2 ; valid for synchronization F_SYNCH: 2 ; valid for synchronization
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) )
These bits are independent and may be combined appropriately, e.g. These bits are independent and may be combined appropriately, e.g.
(F_DISC and F_SYNCH) or (F_DISC and F_NEG) or (F_DISC and F_NEG and (F_DISC and F_SYNCH) or (F_DISC and F_NEG) or (F_DISC and F_NEG and
F_NEG_DRY). F_NEG_DRY).
Note that for a given negotiation session, an objective must be Note that for a given negotiation session, an objective must be
either used for negotiation, or for dry-run negotiation. Mixing the either used for negotiation, or for dry-run negotiation. Mixing the
two modes in a single negotiation is not possible. two modes in a single negotiation is not possible.
3.10.3. General Considerations for Objective Options 2.10.3. General Considerations for Objective Options
As mentioned above, Objective Options MUST be assigned a unique name. As mentioned above, Objective Options MUST be assigned a unique name.
As long as privately defined Objective Options obey the rules above, As long as privately defined Objective Options obey the rules above,
this document does not restrict their choice of name, but the entity this document does not restrict their choice of name, but the entity
or person concerned SHOULD publish the names in use. or person concerned SHOULD publish the names in use.
Names are expressed as UTF-8 strings for convenience in designing Names are expressed as UTF-8 strings for convenience in designing
Objective Options for localized use. For generic usage, names Objective Options for localized use. For generic usage, names
expressed in the ASCII subset of UTF-8 are RECOMMENDED. Designers expressed in the ASCII subset of UTF-8 are RECOMMENDED. Designers
planning to use non-ASCII names are strongly advised to consult planning to use non-ASCII names are strongly advised to consult
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requests. Consequently, the Negotiation Objective options MUST requests. Consequently, the Negotiation Objective options MUST
always be completely presented in a Request Negotiation message, or always be completely presented in a Request Negotiation message, or
in a Discovery message in rapid mode. If there is no initial value, in a Discovery message in rapid mode. If there is no initial value,
the value field SHOULD be set to the 'null' value defined by CBOR. the value field SHOULD be set to the 'null' value defined by CBOR.
Synchronization Objective Options are similar, but MUST be carried by Synchronization Objective Options are similar, but MUST be carried by
Discovery, Discovery Response, Request Synchronization, or Flood Discovery, Discovery Response, Request Synchronization, or Flood
Synchronization messages only. They include value fields only in Synchronization messages only. They include value fields only in
Synchronization or Flood Synchronization messages. Synchronization or Flood Synchronization messages.
3.10.4. Organizing of Objective Options The design of an objective interacts in various ways with the design
of the ASAs that will use it. ASA design considerations are
discussed in [I-D.carpenter-anima-asa-guidelines].
2.10.4. Organizing of Objective Options
Generic objective options MUST be specified in documents available to Generic objective options MUST be specified in documents available to
the public and SHOULD be designed to use either the negotiation or the public and SHOULD be designed to use either the negotiation or
the synchronization mechanism described above. the synchronization mechanism described above.
As noted earlier, one negotiation objective is handled by each GRASP As noted earlier, one negotiation objective is handled by each GRASP
negotiation thread. Therefore, a negotiation objective, which is negotiation thread. Therefore, a negotiation objective, which is
based on a specific function or action, SHOULD be organized as a based on a specific function or action, SHOULD be organized as a
single GRASP option. It is NOT RECOMMENDED to organize multiple single GRASP option. It is NOT RECOMMENDED to organize multiple
negotiation objectives into a single option, nor to split a single negotiation objectives into a single option, nor to split a single
skipping to change at page 43, line 19 skipping to change at page 38, line 19
thread at the same time. Such an ASA would need to stop listening thread at the same time. Such an ASA would need to stop listening
for incoming negotiation requests before generating an outgoing for incoming negotiation requests before generating an outgoing
negotiation request. negotiation request.
A synchronization objective SHOULD be organized as a single GRASP A synchronization objective SHOULD be organized as a single GRASP
option. option.
Some objectives will support more than one operational mode. An Some objectives will support more than one operational mode. An
example is a negotiation objective with both a "dry run" mode (where example is a negotiation objective with both a "dry run" mode (where
the negotiation is to find out whether the other end can in fact make the negotiation is to find out whether the other end can in fact make
the requested change without problems) and a "live" mode. Such modes the requested change without problems) and a "live" mode, as
will be defined in the specification of such an objective. These explained in Section 2.5.5. The semantics of such modes will be
objectives SHOULD include flags indicating the applicable mode(s). defined in the specification of the objectives. These objectives
SHOULD include flags indicating the applicable mode(s).
An issue requiring particular attention is that GRASP itself is a An issue requiring particular attention is that GRASP itself is not a
stateless protocol. Any state associated with a dry run operation, transactionally safe protocol. Any state associated with a dry run
such as temporarily reserving a resource for subsequent use in a live operation, such as temporarily reserving a resource for subsequent
run, is entirely a matter for the designer of the ASA concerned. use in a live run, is entirely a matter for the designer of the ASA
concerned.
As indicated in Section 3.1, an objective's value may include As indicated in Section 2.1, an objective's value may include
multiple parameters. Parameters might be categorized into two multiple parameters. Parameters might be categorized into two
classes: the obligatory ones presented as fixed fields; and the classes: the obligatory ones presented as fixed fields; and the
optional ones presented in some other form of data structure embedded optional ones presented in some other form of data structure embedded
in CBOR. The format might be inherited from an existing management in CBOR. The format might be inherited from an existing management
or configuration protocol, with the objective option acting as a or configuration protocol, with the objective option acting as a
carrier for that format. The data structure might be defined in a carrier for that format. The data structure might be defined in a
formal language, but that is a matter for the specifications of formal language, but that is a matter for the specifications of
individual objectives. There are many candidates, according to the individual objectives. There are many candidates, according to the
context, such as ABNF, RBNF, XML Schema, YANG, etc. The GRASP context, such as ABNF, RBNF, XML Schema, YANG, etc. The GRASP
protocol itself is agnostic on these questions. The only restriction protocol itself is agnostic on these questions. The only restriction
is that the format can be mapped into CBOR. is that the format can be mapped into CBOR.
It is NOT RECOMMENDED to mix parameters that have significantly It is NOT RECOMMENDED to mix parameters that have significantly
different response time characteristics in a single objective. different response time characteristics in a single objective.
Separate objectives are more suitable for such a scenario. Separate objectives are more suitable for such a scenario.
All objectives MUST support GRASP discovery. However, as mentioned All objectives MUST support GRASP discovery. However, as mentioned
in Section 3.3, it is acceptable for an ASA to use an alternative in Section 2.3, it is acceptable for an ASA to use an alternative
method of discovery. method of discovery.
Normally, a GRASP objective will refer to specific technical Normally, a GRASP objective will refer to specific technical
parameters as explained in Section 3.1. However, it is acceptable to parameters as explained in Section 2.1. However, it is acceptable to
define an abstract objective for the purpose of managing or define an abstract objective for the purpose of managing or
coordinating ASAs. It is also acceptable to define a special-purpose coordinating ASAs. It is also acceptable to define a special-purpose
objective for purposes such as trust bootstrapping or formation of objective for purposes such as trust bootstrapping or formation of
the ACP. the ACP.
To guarantee convergence, a limited number of rounds or a timeout is To guarantee convergence, a limited number of rounds or a timeout is
needed for each negotiation objective. Therefore, the definition of needed for each negotiation objective. Therefore, the definition of
each negotiation objective SHOULD clearly specify this, for example a each negotiation objective SHOULD clearly specify this, for example a
default loop count and timeout, so that the negotiation can always be default loop count and timeout, so that the negotiation can always be
terminated properly. If not, the GRASP defaults will apply. terminated properly. If not, the GRASP defaults will apply.
There must be a well-defined procedure for concluding that a There must be a well-defined procedure for concluding that a
negotiation cannot succeed, and if so deciding what happens next negotiation cannot succeed, and if so deciding what happens next
(e.g., deadlock resolution, tie-breaking, or revert to best-effort (e.g., deadlock resolution, tie-breaking, or revert to best-effort
service). This MUST be specified for individual negotiation service). This MUST be specified for individual negotiation
objectives. objectives.
3.10.5. Experimental and Example Objective Options 2.10.5. Experimental and Example Objective Options
The names "EX0" through "EX9" have been reserved for experimental The names "EX0" through "EX9" have been reserved for experimental
options. Multiple names have been assigned because a single options. Multiple names have been assigned because a single
experiment may use multiple options simultaneously. These experiment may use multiple options simultaneously. These
experimental options are highly likely to have different meanings experimental options are highly likely to have different meanings
when used for different experiments. Therefore, they SHOULD NOT be when used for different experiments. Therefore, they SHOULD NOT be
used without an explicit human decision and SHOULD NOT be used in used without an explicit human decision and MUST NOT be used in
unmanaged networks such as home networks. unmanaged networks such as home networks.
These names are also RECOMMENDED for use in documentation examples. These names are also RECOMMENDED for use in documentation examples.
4. Implementation Status [RFC Editor: please remove] 3. Implementation Status [RFC Editor: please remove]
Two prototype implementations of GRASP have been made. Two prototype implementations of GRASP have been made.
4.1. BUPT C++ Implementation 3.1. BUPT C++ Implementation
o Name: BaseNegotiator.cpp, msg.cpp, Client.cpp, Server.cpp o Name: BaseNegotiator.cpp, msg.cpp, Client.cpp, Server.cpp
o Description: C++ implementation of GRASP core and API o Description: C++ implementation of GRASP core and API
o Maturity: Prototype code, interoperable between Ubuntu. o Maturity: Prototype code, interoperable between Ubuntu.
o Coverage: Corresponds to draft-carpenter-anima-gdn-protocol-03. o Coverage: Corresponds to draft-carpenter-anima-gdn-protocol-03.
Since it was implemented based on the old version draft, the most Since it was implemented based on the old version draft, the most
significant limitations comparing to current protocol design significant limitations comparing to current protocol design
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* only coded for IPv6, any IPv4 is accidental * only coded for IPv6, any IPv4 is accidental
o Licensing: Huawei License. o Licensing: Huawei License.
o Experience: https://github.com/liubingpang/IETF-Anima-Signaling- o Experience: https://github.com/liubingpang/IETF-Anima-Signaling-
Protocol/blob/master/README.md Protocol/blob/master/README.md
o Contact: https://github.com/liubingpang/IETF-Anima-Signaling- o Contact: https://github.com/liubingpang/IETF-Anima-Signaling-
Protocol Protocol
4.2. Python Implementation 3.2. Python Implementation
o Name: graspy o Name: graspy
o Description: Python 3 implementation of GRASP core and API. o Description: Python 3 implementation of GRASP core and API.
o Maturity: Prototype code, interoperable between Windows 7 and o Maturity: Prototype code, interoperable between Windows 7 and
Linux. Linux.
o Coverage: Corresponds to draft-ietf-anima-grasp-10. Limitations o Coverage: Corresponds to draft-ietf-anima-grasp-13. Limitations
include: include:
* insecure: uses a dummy ACP module and does not implement TLS * insecure: uses a dummy ACP module
* only coded for IPv6, any IPv4 is accidental * only coded for IPv6, any IPv4 is accidental
* FQDN and URI locators incompletely supported * FQDN and URI locators incompletely supported
* no code for rapid mode * no code for rapid mode
* relay code is lazy (no rate control) * relay code is lazy (no rate control)
* all unicast transactions use TCP (no unicast UDP). * all unicast transactions use TCP (no unicast UDP).
Experimental code for unicast UDP proved to be complex and Experimental code for unicast UDP proved to be complex and
brittle. brittle.
* optional Objective option in Response messages not implemented * optional Objective option in Response messages not implemented
* workarounds for defects in Python socket module and Windows * workarounds for defects in Python socket module and Windows
socket peculiarities socket peculiarities
o Licensing: Simplified BSD o Licensing: Simplified BSD
o Experience: Tested on Windows, Linux and MacOS.
o Experience: https://www.cs.auckland.ac.nz/~brian/graspy/graspy.pdf https://www.cs.auckland.ac.nz/~brian/graspy/graspy.pdf
o Contact: https://www.cs.auckland.ac.nz/~brian/graspy/ o Contact: https://www.cs.auckland.ac.nz/~brian/graspy/
5. Security Considerations 4. Security Considerations
A successful attack on negotiation-enabled nodes would be extremely A successful attack on negotiation-enabled nodes would be extremely
harmful, as such nodes might end up with a completely undesirable harmful, as such nodes might end up with a completely undesirable
configuration that would also adversely affect their peers. GRASP configuration that would also adversely affect their peers. GRASP
nodes and messages therefore require full protection. As explained nodes and messages therefore require full protection. As explained
in Section 3.5.1, GRASP MUST run within a secure environment such as in Section 2.5.1, GRASP MUST run within a secure environment such as
the Autonomic Control Plane [I-D.ietf-anima-autonomic-control-plane], the Autonomic Control Plane [I-D.ietf-anima-autonomic-control-plane],
except for the constrained instances described in Section 3.5.2. except for the constrained instances described in Section 2.5.2.
- Authentication - Authentication
A cryptographically authenticated identity for each device is A cryptographically authenticated identity for each device is
needed in an autonomic network. It is not safe to assume that a needed in an autonomic network. It is not safe to assume that a
large network is physically secured against interference or that large network is physically secured against interference or that
all personnel are trustworthy. Each autonomic node MUST be all personnel are trustworthy. Each autonomic node MUST be
capable of proving its identity and authenticating its messages. capable of proving its identity and authenticating its messages.
GRASP relies on a separate external certificate-based security GRASP relies on a separate external certificate-based security
mechanism to support authentication, data integrity protection, mechanism to support authentication, data integrity protection,
and anti-replay protection. and anti-replay protection.
Since GRASP must be deployed in an existing secure environment, Since GRASP must be deployed in an existing secure environment,
the protocol itself specifies nothing concerning the trust anchor the protocol itself specifies nothing concerning the trust anchor
and certification authority. and certification authority. For example, in the Autonomic
Control Plane [I-D.ietf-anima-autonomic-control-plane], all nodes
can trust each other and the ASAs installed in them.
If GRASP is used temporarily without an external security If GRASP is used temporarily without an external security
mechanism, for example during system bootstrap (Section 3.5.1), mechanism, for example during system bootstrap (Section 2.5.1),
the Session ID (Section 3.7) will act as a nonce to provide the Session ID (Section 2.7) will act as a nonce to provide
limited protection against third parties injecting responses. A limited protection against third parties injecting responses. A
full analysis of the secure bootstrap process is in full analysis of the secure bootstrap process is in
[I-D.ietf-anima-bootstrapping-keyinfra]. [I-D.ietf-anima-bootstrapping-keyinfra].
- Authorization and Roles - Authorization and Roles
The GRASP protocol is agnostic about the roles and capabilities of The GRASP protocol is agnostic about the roles and capabilities of
individual ASAs and about which objectives a particular ASA is individual ASAs and about which objectives a particular ASA is
authorized to support. An implementation might support authorized to support. An implementation might support
precautions such as allowing only one ASA in a given node to precautions such as allowing only one ASA in a given node to
modify a given objective, but this may not be appropriate in all modify a given objective, but this may not be appropriate in all
cases. For example, it might be operationally useful to allow an cases. For example, it might be operationally useful to allow an
old and a new version of the same ASA to run simultaneously during old and a new version of the same ASA to run simultaneously during
an overlap period. These questions are out of scope for the an overlap period. These questions are out of scope for the
present specification. present specification.
- Privacy and confidentiality - Privacy and confidentiality
Generally speaking, no personal information is expected to be GRASP is intended for network management purposes involving
involved in the signaling protocol, so there should be no direct network elements, not end hosts. Therefore, no personal
impact on personal privacy. Nevertheless, traffic flow paths, information is expected to be involved in the signaling protocol,
VPNs, etc. could be negotiated, which could be of interest for so there should be no direct impact on personal privacy.
traffic analysis. Also, operators generally want to conceal Nevertheless, applications that do convey personal information
details of their network topology and traffic density from cannot be excluded. Also, traffic flow paths, VPNs, etc. could be
outsiders. Therefore, since insider attacks cannot be excluded in negotiated, which could be of interest for traffic analysis.
a large network, the security mechanism for the protocol MUST Operators generally want to conceal details of their network
provide message confidentiality. This is why Section 3.5.1 topology and traffic density from outsiders. Therefore, since
requires either an ACP or an alternative security mechanism. insider attacks cannot be excluded in a large network, the
security mechanism for the protocol MUST provide message
confidentiality. This is why Section 2.5.1 requires either an ACP
or an alternative security mechanism.
- Link-local multicast security - Link-local multicast security
GRASP has no reasonable alternative to using link-local multicast GRASP has no reasonable alternative to using link-local multicast
for Discovery or Flood Synchronization messages and these messages for Discovery or Flood Synchronization messages and these messages
are sent in clear and with no authentication. They are only sent are sent in clear and with no authentication. They are only sent
on interfaces within the autonomic network (see Section 3.1 and on interfaces within the autonomic network (see Section 2.1 and
Section 3.5.1). They are however available to on-link Section 2.5.1). They are however available to on-link
eavesdroppers, and could be forged by on-link attackers. In the eavesdroppers, and could be forged by on-link attackers. In the
case of Discovery, the Discovery Responses are unicast and will case of Discovery, the Discovery Responses are unicast and will
therefore be protected (Section 3.5.1), and an untrusted forger therefore be protected (Section 2.5.1), and an untrusted forger
will not be able to receive responses. In the case of Flood will not be able to receive responses. In the case of Flood
Synchronization, an on-link eavesdropper will be able to receive Synchronization, an on-link eavesdropper will be able to receive
the flooded objectives but there is no response message to the flooded objectives but there is no response message to
consider. Some precautions for Flood Synchronization messages are consider. Some precautions for Flood Synchronization messages are
suggested in Section 3.5.6.2. suggested in Section 2.5.6.2.
- DoS Attack Protection - DoS Attack Protection
GRASP discovery partly relies on insecure link-local multicast. GRASP discovery partly relies on insecure link-local multicast.
Since routers participating in GRASP sometimes relay discovery Since routers participating in GRASP sometimes relay discovery
messages from one link to another, this could be a vector for messages from one link to another, this could be a vector for
denial of service attacks. Some mitigations are specified in denial of service attacks. Some mitigations are specified in
Section 3.5.4. However, malicious code installed inside the Section 2.5.4. However, malicious code installed inside the
Autonomic Control Plane could always launch DoS attacks consisting Autonomic Control Plane could always launch DoS attacks consisting
of spurious discovery messages, or of spurious discovery of spurious discovery messages, or of spurious discovery
responses. It is important that firewalls prevent any GRASP responses. It is important that firewalls prevent any GRASP
messages from entering the domain from an unknown source. messages from entering the domain from an unknown source.
- Security during bootstrap and discovery - Security during bootstrap and discovery
A node cannot trust GRASP traffic from other nodes until the A node cannot trust GRASP traffic from other nodes until the
security environment (such as the ACP) has identified the trust security environment (such as the ACP) has identified the trust
anchor and can authenticate traffic by validating certificates for anchor and can authenticate traffic by validating certificates for
other nodes. Also, until it has succesfully enrolled other nodes. Also, until it has succesfully enrolled
[I-D.ietf-anima-bootstrapping-keyinfra] a node cannot assume that [I-D.ietf-anima-bootstrapping-keyinfra] a node cannot assume that
other nodes are able to authenticate its own traffic. Therefore, other nodes are able to authenticate its own traffic. Therefore,
GRASP discovery during the bootstrap phase for a new device will GRASP discovery during the bootstrap phase for a new device will
inevitably be insecure. Secure synchronization and negotiation inevitably be insecure. Secure synchronization and negotiation
will be impossible until enrollment is complete. Further details will be impossible until enrollment is complete. Further details
are given in Section 3.5.2. are given in Section 2.5.2.
- Security of discovered locators - Security of discovered locators
When GRASP discovery returns an IP address, it MUST be that of a When GRASP discovery returns an IP address, it MUST be that of a
node within the secure environment (Section 3.5.1). If it returns node within the secure environment (Section 2.5.1). If it returns
an FQDN or a URI, the ASA that receives it MUST NOT assume that an FQDN or a URI, the ASA that receives it MUST NOT assume that
the target of the locator is within the secure environment. the target of the locator is within the secure environment.
6. CDDL Specification of GRASP 5. CDDL Specification of GRASP
<CODE BEGINS> <CODE BEGINS>
grasp-message = (message .within message-structure) / noop-message grasp-message = (message .within message-structure) / noop-message
message-structure = [MESSAGE_TYPE, session-id, ?initiator, message-structure = [MESSAGE_TYPE, session-id, ?initiator,
*grasp-option] *grasp-option]
MESSAGE_TYPE = 0..255 MESSAGE_TYPE = 0..255
session-id = 0..4294967295 ;up to 32 bits session-id = 0..4294967295 ;up to 32 bits
grasp-option = any grasp-option = any
message /= discovery-message message /= discovery-message
discovery-message = [M_DISCOVERY, session-id, initiator, objective] discovery-message = [M_DISCOVERY, session-id, initiator, objective]
message /= response-message ;response to Discovery message /= response-message ;response to Discovery
response-message = [M_RESPONSE, session-id, initiator, ttl, response-message = [M_RESPONSE, session-id, initiator, ttl,
(+locator-option // divert-option), ?objective] (+locator-option // divert-option), ?objective]
message /= synch-message ;response to Synchronization request message /= synch-message ;response to Synchronization request
synch-message = [M_SYNCH, session-id, objective] synch-message = [M_SYNCH, session-id, objective]
message /= flood-message message /= flood-message
flood-message = [M_FLOOD, session-id, initiator, ttl, flood-message = [M_FLOOD, session-id, initiator, ttl,
+[objective, (locator-option / [])]] +[objective, (locator-option / [])]]
message /= request-negotiation-message message /= request-negotiation-message
request-negotiation-message = [M_REQ_NEG, session-id, objective] request-negotiation-message = [M_REQ_NEG, session-id, objective]
message /= request-synchronization-message message /= request-synchronization-message
request-synchronization-message = [M_REQ_SYN, session-id, objective] request-synchronization-message = [M_REQ_SYN, session-id, objective]
message /= negotiation-message message /= negotiation-message
negotiation-message = [M_NEGOTIATE, session-id, objective] negotiation-message = [M_NEGOTIATE, session-id, objective]
message /= end-message message /= end-message
end-message = [M_END, session-id, accept-option / decline-option ] end-message = [M_END, session-id, accept-option / decline-option ]
message /= wait-message
wait-message = [M_WAIT, session-id, waiting-time]
message /= invalid-message message /= wait-message
invalid-message = [M_INVALID, session-id, ?any] wait-message = [M_WAIT, session-id, waiting-time]
noop-message = [M_NOOP] message /= invalid-message
invalid-message = [M_INVALID, session-id, ?any]
divert-option = [O_DIVERT, +locator-option] noop-message = [M_NOOP]
accept-option = [O_ACCEPT] divert-option = [O_DIVERT, +locator-option]
decline-option = [O_DECLINE, ?reason] accept-option = [O_ACCEPT]
reason = text ;optional error message
waiting-time = 0..4294967295 ; in milliseconds decline-option = [O_DECLINE, ?reason]
ttl = 0..4294967295 ; in milliseconds reason = text ;optional UTF-8 error message
locator-option /= [O_IPv4_LOCATOR, ipv4-address, waiting-time = 0..4294967295 ; in milliseconds
transport-proto, port-number] ttl = 0..4294967295 ; in milliseconds
ipv4-address = bytes .size 4
locator-option /= [O_IPv6_LOCATOR, ipv6-address, locator-option /= [O_IPv4_LOCATOR, ipv4-address,
transport-proto, port-number] transport-proto, port-number]
ipv6-address = bytes .size 16 ipv4-address = bytes .size 4
locator-option /= [O_FQDN_LOCATOR, text, transport-proto, port-number] locator-option /= [O_IPv6_LOCATOR, ipv6-address,
transport-proto, port-number]
ipv6-address = bytes .size 16
transport-proto = IPPROTO_TCP / IPPROTO_UDP locator-option /= [O_FQDN_LOCATOR, text, transport-proto, port-number]
IPPROTO_TCP = 6
IPPROTO_UDP = 17
port-number = 0..65535
locator-option /= [O_URI_LOCATOR, text] locator-option /= [O_URI_LOCATOR, text,
transport-proto / null, port-number / null]
initiator = ipv4-address / ipv6-address transport-proto = IPPROTO_TCP / IPPROTO_UDP
IPPROTO_TCP = 6
IPPROTO_UDP = 17
port-number = 0..65535
objective-flags = uint .bits objective-flag initiator = ipv4-address / ipv6-address
objective-flag = &( objective-flags = uint .bits objective-flag
F_DISC: 0 ; valid for discovery objective-flag = &(
F_NEG: 1 ; valid for negotiation F_DISC: 0 ; valid for discovery
F_SYNCH: 2 ; valid for synchronization F_NEG: 1 ; valid for negotiation
F_NEG_DRY: 3 ; negotiation is dry-run F_SYNCH: 2 ; valid for synchronization
) F_NEG_DRY: 3 ; negotiation is dry-run
)
objective = [objective-name, objective-flags, loop-count, ?any] objective = [objective-name, objective-flags, loop-count, ?objective-value]
objective-name = text ;see specification for uniqueness rules
loop-count = 0..255 objective-name = text ;see section "Format of Objective Options"
; Constants for message types and option types objective-value = any
M_NOOP = 0 loop-count = 0..255
M_DISCOVERY = 1
M_RESPONSE = 2
M_REQ_NEG = 3
M_REQ_SYN = 4
M_NEGOTIATE = 5
M_END = 6
M_WAIT = 7
M_SYNCH = 8
M_FLOOD = 9
M_INVALID = 99
O_DIVERT = 100 ; Constants for message types and option types
O_ACCEPT = 101
O_DECLINE = 102
O_IPv6_LOCATOR = 103
O_IPv4_LOCATOR = 104
O_FQDN_LOCATOR = 105
O_URI_LOCATOR = 106
<CODE ENDS>
7. IANA Considerations M_NOOP = 0
M_DISCOVERY = 1
M_RESPONSE = 2
M_REQ_NEG = 3
M_REQ_SYN = 4
M_NEGOTIATE = 5
M_END = 6
M_WAIT = 7
M_SYNCH = 8
M_FLOOD = 9
M_INVALID = 99
O_DIVERT = 100
O_ACCEPT = 101
O_DECLINE = 102
O_IPv6_LOCATOR = 103
O_IPv4_LOCATOR = 104
O_FQDN_LOCATOR = 105
O_URI_LOCATOR = 106
<CODE ENDS>
6. IANA Considerations
This document defines the GeneRic Autonomic Signaling Protocol This document defines the GeneRic Autonomic Signaling Protocol
(GRASP). (GRASP).
Section 3.6 explains the following link-local multicast addresses, Section 2.6 explains the following link-local multicast addresses,
which IANA is requested to assign for use by GRASP: which IANA is requested to assign for use by GRASP:
ALL_GRASP_NEIGHBORS multicast address (IPv6): (TBD1). Assigned in ALL_GRASP_NEIGHBORS multicast address (IPv6): (TBD1). Assigned in
the IPv6 Link-Local Scope Multicast Addresses registry. the IPv6 Link-Local Scope Multicast Addresses registry.
ALL_GRASP_NEIGHBORS multicast address (IPv4): (TBD2). Assigned in ALL_GRASP_NEIGHBORS multicast address (IPv4): (TBD2). Assigned in
the IPv4 Multicast Local Network Control Block. the IPv4 Multicast Local Network Control Block.
Section 3.6 explains the following User Port, which IANA is requested Section 2.6 explains the following User Port, which IANA is requested
to assign for use by GRASP for both UDP and TCP: to assign for use by GRASP for both UDP and TCP:
GRASP_LISTEN_PORT: (TBD3) GRASP_LISTEN_PORT: (TBD3)
Service Name: Generic Autonomic Signaling Protocol (GRASP) Service Name: Generic Autonomic Signaling Protocol (GRASP)
Transport Protocols: UDP, TCP Transport Protocols: UDP, TCP
Assignee: iesg@ietf.org Assignee: iesg@ietf.org
Contact: chair@ietf.org Contact: chair@ietf.org
Description: See Section 3.6 Description: See Section 2.6
Reference: RFC XXXX (this document) Reference: RFC XXXX (this document)
The IANA is requested to create a GRASP Parameter Registry including The IANA is requested to create a GRASP Parameter Registry including
two registry tables. These are the GRASP Messages and Options two registry tables. These are the GRASP Messages and Options
Table and the GRASP Objective Names Table. Table and the GRASP Objective Names Table.
GRASP Messages and Options Table. The values in this table are names GRASP Messages and Options Table. The values in this table are names
paired with decimal integers. Future values MUST be assigned using paired with decimal integers. Future values MUST be assigned using
the Standards Action policy defined by [RFC5226]. The following the Standards Action policy defined by [RFC5226]. The following
initial values are assigned by this document: initial values are assigned by this document:
skipping to change at page 51, line 38 skipping to change at page 46, line 49
O_DIVERT = 100 O_DIVERT = 100
O_ACCEPT = 101 O_ACCEPT = 101
O_DECLINE = 102 O_DECLINE = 102
O_IPv6_LOCATOR = 103 O_IPv6_LOCATOR = 103
O_IPv4_LOCATOR = 104 O_IPv4_LOCATOR = 104
O_FQDN_LOCATOR = 105 O_FQDN_LOCATOR = 105
O_URI_LOCATOR = 106 O_URI_LOCATOR = 106
GRASP Objective Names Table. The values in this table are UTF-8 GRASP Objective Names Table. The values in this table are UTF-8
strings. Future values MUST be assigned using the Specification strings which MUST NOT include a colon (":"), according to
Required policy defined by [RFC5226]. Section 2.10.1. Future values MUST be assigned using the
Specification Required policy defined by [RFC5226].
To assist expert review of a new objective, the specification should To assist expert review of a new objective, the specification should
include a precise description of the format of the new objective, include a precise description of the format of the new objective,
with sufficient explanation of its semantics to allow independent with sufficient explanation of its semantics to allow independent
implementations. See Section 3.10.3 for more details. If the new implementations. See Section 2.10.3 for more details. If the new
objective is similar in name or purpose to a previously registered objective is similar in name or purpose to a previously registered
objective, the specification should explain why a new objective is objective, the specification should explain why a new objective is
justified. justified.
The following initial values are assigned by this document: The following initial values are assigned by this document:
EX0 EX0
EX1 EX1
EX2 EX2
EX3 EX3
EX4 EX4
EX5 EX5
EX6 EX6
EX7 EX7
EX8 EX8
EX9 EX9
8. Acknowledgements 7. Acknowledgements
A major contribution to the original version of this document was A major contribution to the original version of this document was
made by Sheng Jiang. Significant review inputs were received from made by Sheng Jiang. Significant early review inputs were received
Toerless Eckert, Joel Halpern, Barry Leiba, Charles E. Perkins, and from Toerless Eckert, Joel Halpern, Barry Leiba, Charles E. Perkins,
Michael Richardson. and Michael Richardson. William Atwood provided important assistance
in debugging a prototype implementation.
Valuable comments were received from Michael Behringer, Jeferson Valuable comments were received from Michael Behringer, Jeferson
Campos Nobre, Laurent Ciavaglia, Zongpeng Du, Yu Fu, Joel Jaeggli, Campos Nobre, Laurent Ciavaglia, Zongpeng Du, Yu Fu, Joel Jaeggli,
Zhenbin Li, Dimitri Papadimitriou, Pierre Peloso, Reshad Rahman, Zhenbin Li, Dimitri Papadimitriou, Pierre Peloso, Reshad Rahman,
Markus Stenberg, Rene Struik, Martin Thomson, Dacheng Zhang, and Markus Stenberg, Martin Stiemerling, Rene Struik, Martin Thomson,
other participants in the NMRG research group and the ANIMA working Dacheng Zhang, and participants in the NMRG research group, the ANIMA
group. working group, and the IESG.
9. References 8. References
9.1. Normative References 8.1. Normative References
[I-D.greevenbosch-appsawg-cbor-cddl] [I-D.greevenbosch-appsawg-cbor-cddl]
Birkholz, H., Vigano, C., and C. Bormann, "CBOR data Birkholz, H., Vigano, C., and C. Bormann, "CBOR data
definition language (CDDL): a notational convention to definition language (CDDL): a notational convention to
express CBOR data structures", draft-greevenbosch-appsawg- express CBOR data structures", draft-greevenbosch-appsawg-
cbor-cddl-10 (work in progress), March 2017. cbor-cddl-10 (work in progress), March 2017.
[I-D.ietf-anima-autonomic-control-plane] [I-D.ietf-anima-autonomic-control-plane]
Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
Control Plane", draft-ietf-anima-autonomic-control- Control Plane", draft-ietf-anima-autonomic-control-
plane-06 (work in progress), March 2017. plane-06 (work in progress), March 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <http://www.rfc-editor.org/info/rfc3629>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>. <http://www.rfc-editor.org/info/rfc3986>.
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005, DOI 10.17487/RFC4086, June 2005,
<http://www.rfc-editor.org/info/rfc4086>. <http://www.rfc-editor.org/info/rfc4086>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <http://www.rfc-editor.org/info/rfc7049>. October 2013, <http://www.rfc-editor.org/info/rfc7049>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque [RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217, Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014, DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>. <http://www.rfc-editor.org/info/rfc7217>.
9.2. Informative References [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <http://www.rfc-editor.org/info/rfc8085>.
8.2. Informative References
[I-D.carpenter-anima-asa-guidelines]
Carpenter, B. and S. Jiang, "Guidelines for Autonomic
Service Agents", draft-carpenter-anima-asa-guidelines-01
(work in progress), January 2017.
[I-D.chaparadza-intarea-igcp] [I-D.chaparadza-intarea-igcp]
Behringer, M., Chaparadza, R., Petre, R., Li, X., and H. Behringer, M., Chaparadza, R., Petre, R., Li, X., and H.
Mahkonen, "IP based Generic Control Protocol (IGCP)", Mahkonen, "IP based Generic Control Protocol (IGCP)",
draft-chaparadza-intarea-igcp-00 (work in progress), July draft-chaparadza-intarea-igcp-00 (work in progress), July
2011. 2011.
[I-D.ietf-anima-bootstrapping-keyinfra] [I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Behringer, M., Bjarnason, Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
S., and K. Watsen, "Bootstrapping Remote Secure Key S., and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
keyinfra-05 (work in progress), March 2017. keyinfra-06 (work in progress), May 2017.
[I-D.ietf-anima-reference-model] [I-D.ietf-anima-reference-model]
Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L., Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
Pierre, P., Liu, B., Nobre, J., and J. Strassner, "A Pierre, P., Liu, B., Nobre, J., and J. Strassner, "A
Reference Model for Autonomic Networking", draft-ietf- Reference Model for Autonomic Networking", draft-ietf-
anima-reference-model-03 (work in progress), March 2017. anima-reference-model-03 (work in progress), March 2017.
[I-D.ietf-anima-stable-connectivity] [I-D.ietf-anima-stable-connectivity]
Eckert, T. and M. Behringer, "Using Autonomic Control Eckert, T. and M. Behringer, "Using Autonomic Control
Plane for Stable Connectivity of Network OAM", draft-ietf- Plane for Stable Connectivity of Network OAM", draft-ietf-
skipping to change at page 55, line 5 skipping to change at page 50, line 20
[RFC2608] Guttman, E., Perkins, C., Veizades, J., and M. Day, [RFC2608] Guttman, E., Perkins, C., Veizades, J., and M. Day,
"Service Location Protocol, Version 2", RFC 2608, "Service Location Protocol, Version 2", RFC 2608,
DOI 10.17487/RFC2608, June 1999, DOI 10.17487/RFC2608, June 1999,
<http://www.rfc-editor.org/info/rfc2608>. <http://www.rfc-editor.org/info/rfc2608>.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", "Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, DOI 10.17487/RFC2865, June 2000, RFC 2865, DOI 10.17487/RFC2865, June 2000,
<http://www.rfc-editor.org/info/rfc2865>. <http://www.rfc-editor.org/info/rfc2865>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<http://www.rfc-editor.org/info/rfc3209>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <http://www.rfc-editor.org/info/rfc3315>. 2003, <http://www.rfc-editor.org/info/rfc3315>.
[RFC3416] Presuhn, R., Ed., "Version 2 of the Protocol Operations [RFC3416] Presuhn, R., Ed., "Version 2 of the Protocol Operations
for the Simple Network Management Protocol (SNMP)", for the Simple Network Management Protocol (SNMP)",
STD 62, RFC 3416, DOI 10.17487/RFC3416, December 2002, STD 62, RFC 3416, DOI 10.17487/RFC3416, December 2002,
<http://www.rfc-editor.org/info/rfc3416>. <http://www.rfc-editor.org/info/rfc3416>.
[RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W.
Stevens, "Basic Socket Interface Extensions for IPv6",
RFC 3493, DOI 10.17487/RFC3493, February 2003,
<http://www.rfc-editor.org/info/rfc3493>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>. <http://www.rfc-editor.org/info/rfc4861>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
skipping to change at page 61, line 15 skipping to change at page 56, line 25
o 25. Does GDNP discovery meet the needs of multi-hop DNS-SD? o 25. Does GDNP discovery meet the needs of multi-hop DNS-SD?
RESOLVED: Decided not to consider this further as a GRASP protocol RESOLVED: Decided not to consider this further as a GRASP protocol
issue. GRASP objectives could embed DNS-SD formats if needed. issue. GRASP objectives could embed DNS-SD formats if needed.
o 26. Add a URL type to the locator options (for security bootstrap o 26. Add a URL type to the locator options (for security bootstrap
etc.) etc.)
RESOLVED: Done, later renamed as URI. RESOLVED: Done, later renamed as URI.
o 27. Security of Flood multicasts (Section 3.5.6.2). o 27. Security of Flood multicasts (Section 2.5.6.2).
RESOLVED: added text. RESOLVED: added text.
o 28. Does ACP support secure link-local multicast? o 28. Does ACP support secure link-local multicast?
RESOLVED by new text in the Security Considerations. RESOLVED by new text in the Security Considerations.
o 29. PEN is used to distinguish vendor options. Would it be o 29. PEN is used to distinguish vendor options. Would it be
better to use a domain name? Anything unique will do. better to use a domain name? Anything unique will do.
skipping to change at page 63, line 44 skipping to change at page 59, line 5
two different messages (and adjust various message names two different messages (and adjust various message names
accordingly)? accordingly)?
RESOLVED: Yes. Done. RESOLVED: Yes. Done.
o 48. Should the Appendix "Capability Analysis of Current o 48. Should the Appendix "Capability Analysis of Current
Protocols" be deleted before RFC publication? Protocols" be deleted before RFC publication?
RESOLVED: No (per WG meeting at IETF 96). RESOLVED: No (per WG meeting at IETF 96).
o 49. Section 3.5.1 Should say more about signaling between two o 49. Section 2.5.1 Should say more about signaling between two
autonomic networks/domains. autonomic networks/domains.
RESOLVED: Description of separate GRASP instance added. RESOLVED: Description of separate GRASP instance added.
o 50. Is Rapid mode limited to on-link only? What happens if first o 50. Is Rapid mode limited to on-link only? What happens if first
discovery responder does not support Rapid Mode? Section 3.5.5, discovery responder does not support Rapid Mode? Section 2.5.5,
Section 3.5.6) Section 2.5.6)
RESOLVED: Not limited to on-link. First responder wins. RESOLVED: Not limited to on-link. First responder wins.
o 51. Should flooded objectives have a time-to-live before they are o 51. Should flooded objectives have a time-to-live before they are
deleted from the flood cache? And should they be tagged in the deleted from the flood cache? And should they be tagged in the
cache with their source locator? cache with their source locator?
RESOLVED: TTL added to Flood (and Discovery Response) messages. RESOLVED: TTL added to Flood (and Discovery Response) messages.
Cached flooded objectives must be tagged with their originating Cached flooded objectives must be tagged with their originating
ASA locator, and multiple copies must be kept if necessary. ASA locator, and multiple copies must be kept if necessary.
skipping to change at page 65, line 15 skipping to change at page 60, line 24
o 61. Is the SONN constrained instance really needed? o 61. Is the SONN constrained instance really needed?
RESOLVED: Retained but only as an option. RESOLVED: Retained but only as an option.
o 62. Is it helpful to tag descriptive text with message names o 62. Is it helpful to tag descriptive text with message names
(M_DISCOVER etc.)? (M_DISCOVER etc.)?
RESOLVED: Yes, done in various parts of the text. RESOLVED: Yes, done in various parts of the text.
o 63. Should encryption be MUST instead of SHOULD in Section 3.5.1 o 63. Should encryption be MUST instead of SHOULD in Section 2.5.1
and Section 3.5.2.1? and Section 2.5.2.1?
RESOLVED: Yes, MUST implement in both cases. RESOLVED: Yes, MUST implement in both cases.
o 64. Should more security text be moved from the main text into o 64. Should more security text be moved from the main text into
the Security Considerations? the Security Considerations?
RESOLVED: No, on AD advice. RESOLVED: No, on AD advice.
o 65. Do we need to formally restrict Unicode characters allowed in o 65. Do we need to formally restrict Unicode characters allowed in
objective names? objective names?
skipping to change at page 65, line 41 skipping to change at page 61, line 7
RESOLVED: No, on AD advice. RESOLVED: No, on AD advice.
o 67. Remove normative dependency on draft-greevenbosch-appsawg- o 67. Remove normative dependency on draft-greevenbosch-appsawg-
cbor-cddl? cbor-cddl?
RESOLVED: No, on AD advice. In worst case, fix at AUTH48. RESOLVED: No, on AD advice. In worst case, fix at AUTH48.
Appendix C. Change log [RFC Editor: Please remove] Appendix C. Change log [RFC Editor: Please remove]
draft-ietf-anima-grasp-13, 2017-06-06:
Updates following additional IESG comments:
Removed all mention of TLS, including SONN, since it was under-
specified.
Clarified other text about trust and security model.
Banned Rapid Mode when multicast is insecure.
Explained use of M_INVALID to support extensibility
Corrected details on discovery cache TTL and discovery timeout.
Improved description of multicast UDP w.r.t. RFC8085.
Clarified when transport connections are opened or closed.
Noted that IPPROTO values come from the Protocol Numbers registry
Protocol change: Added protocol and port numbers to URI locator.
Removed inaccurate text about routing protocols
Moved Requirements section to an Appendix.
Other editorial and technical clarifications.
draft-ietf-anima-grasp-12, 2017-05-19: draft-ietf-anima-grasp-12, 2017-05-19:
Updates following IESG comments: Updates following IESG comments:
Clarified that GRASP runs in a single addressing realm Clarified that GRASP runs in a single addressing realm
Improved wording about FQDN resolution, clarified that URI usage is Improved wording about FQDN resolution, clarified that URI usage is
out of scope. out of scope.
Clarified description of negotiation timeout. Clarified description of negotiation timeout.
skipping to change at page 72, line 30 skipping to change at page 68, line 25
expanded future work list, 2015-01-06. expanded future work list, 2015-01-06.
draft-carpenter-anima-gdn-protocol-00, combination of draft-jiang- draft-carpenter-anima-gdn-protocol-00, combination of draft-jiang-
config-negotiation-ps-03 and draft-jiang-config-negotiation-protocol- config-negotiation-ps-03 and draft-jiang-config-negotiation-protocol-
02, 2014-10-08. 02, 2014-10-08.
Appendix D. Example Message Formats Appendix D. Example Message Formats
For readers unfamiliar with CBOR, this appendix shows a number of For readers unfamiliar with CBOR, this appendix shows a number of
example GRASP messages conforming to the CDDL syntax given in example GRASP messages conforming to the CDDL syntax given in
Section 6. Each message is shown three times in the following Section 5. Each message is shown three times in the following
formats: formats:
1. CBOR diagnostic notation. 1. CBOR diagnostic notation.
2. Similar, but showing the names of the constants. (Details of the 2. Similar, but showing the names of the constants. (Details of the
flag bit encoding are omitted.) flag bit encoding are omitted.)
3. Hexadecimal version of the CBOR wire format. 3. Hexadecimal version of the CBOR wire format.
Long lines are split for display purposes only. Long lines are split for display purposes only.
skipping to change at page 75, line 8 skipping to change at page 71, line 4
[5, 13767778, ["EX3", 3, 3, ["NZD", 246]]] [5, 13767778, ["EX3", 3, 3, ["NZD", 246]]]
[M_NEGOTIATE, 13767778, ["EX3", F_NEG_bits, 3, ["NZD", 246]]] [M_NEGOTIATE, 13767778, ["EX3", F_NEG_bits, 3, ["NZD", 246]]]
h'83051a00d214628463455833030382634e5a4418f6' h'83051a00d214628463455833030382634e5a4418f6'
The responder refuses to negotiate further: The responder refuses to negotiate further:
[6, 13767778, [102, "Insufficient funds"]] [6, 13767778, [102, "Insufficient funds"]]
[M_END , 13767778, [O_DECLINE, "Insufficient funds"]] [M_END , 13767778, [O_DECLINE, "Insufficient funds"]]
h'83061a00d2146282186672496e73756666696369656e742066756e6473' h'83061a00d2146282186672496e73756666696369656e742066756e6473'
This negotiation has failed. If either side had sent [M_END, This negotiation has failed. If either side had sent [M_END,
13767778, [O_ACCEPT]] it would have succeeded, converging on the 13767778, [O_ACCEPT]] it would have succeeded, converging on the
objective value in the preceding M_NEGOTIATE. Note that apart from objective value in the preceding M_NEGOTIATE. Note that apart from
the initial M_REQ_NEG, the process is symmetrical. the initial M_REQ_NEG, the process is symmetrical.
Appendix E. Capability Analysis of Current Protocols Appendix E. Requirement Analysis of Discovery, Synchronization and
Negotiation
This section discusses the requirements for discovery, negotiation
and synchronization capabilities. The primary user of the protocol
is an autonomic service agent (ASA), so the requirements are mainly
expressed as the features needed by an ASA. A single physical device
might contain several ASAs, and a single ASA might manage several
technical objectives. If a technical objective is managed by several
ASAs, any necessary coordination is outside the scope of the GRASP
signaling protocol. Furthermore, requirements for ASAs themselves,
such as the processing of Intent [RFC7575], are out of scope for the
present document.
E.1. Requirements for Discovery
D1. ASAs may be designed to manage any type of configurable device
or software, as required in Appendix E.2. A basic requirement is
therefore that the protocol can represent and discover any kind of
technical objective (as defined in Section 2.1) among arbitrary
subsets of participating nodes.
In an autonomic network we must assume that when a device starts up
it has no information about any peer devices, the network structure,
or what specific role it must play. The ASA(s) inside the device are
in the same situation. In some cases, when a new application session
starts up within a device, the device or ASA may again lack
information about relevant peers. For example, it might be necessary
to set up resources on multiple other devices, coordinated and
matched to each other so that there is no wasted resource. Security
settings might also need updating to allow for the new device or
user. The relevant peers may be different for different technical
objectives. Therefore discovery needs to be repeated as often as
necessary to find peers capable of acting as counterparts for each
objective that a discovery initiator needs to handle. From this
background we derive the next three requirements:
D2. When an ASA first starts up, it may have no knowledge of the
specific network to which it is attached. Therefore the discovery
process must be able to support any network scenario, assuming only
that the device concerned is bootstrapped from factory condition.
D3. When an ASA starts up, it must require no configured location
information about any peers in order to discover them.
D4. If an ASA supports multiple technical objectives, relevant peers
may be different for different discovery objectives, so discovery
needs to be performed separately to find counterparts for each
objective. Thus, there must be a mechanism by which an ASA can
separately discover peer ASAs for each of the technical objectives
that it needs to manage, whenever necessary.
D5. Following discovery, an ASA will normally perform negotiation or
synchronization for the corresponding objectives. The design should
allow for this by conveniently linking discovery to negotiation and
synchronization. It may provide an optional mechanism to combine
discovery and negotiation/synchronization in a single protocol
exchange.
D6. Some objectives may only be significant on the local link, but
others may be significant across the routed network and require off-
link operations. Thus, the relevant peers might be immediate
neighbors on the same layer 2 link, or they might be more distant and
only accessible via layer 3. The mechanism must therefore provide
both on-link and off-link discovery of ASAs supporting specific
technical objectives.
D7. The discovery process should be flexible enough to allow for
special cases, such as the following:
o During initialization, a device must be able to establish mutual
trust with autonomic nodes elsewhere in the network and
participate in an authentication mechanism. Although this will
inevitably start with a discovery action, it is a special case
precisely because trust is not yet established. This topic is the
subject of [I-D.ietf-anima-bootstrapping-keyinfra]. We require
that once trust has been established for a device, all ASAs within
the device inherit the device's credentials and are also trusted.
This does not preclude the device having multiple credentials.
o Depending on the type of network involved, discovery of other
central functions might be needed, such as the Network Operations
Center (NOC) [I-D.ietf-anima-stable-connectivity]. The protocol
must be capable of supporting such discovery during
initialization, as well as discovery during ongoing operation.
D8. The discovery process must not generate excessive traffic and
must take account of sleeping nodes.
D9. There must be a mechanism for handling stale discovery results.
E.2. Requirements for Synchronization and Negotiation Capability
Autonomic networks need to be able to manage many different types of
parameter and consider many dimensions, such as latency, load, unused
or limited resources, conflicting resource requests, security
settings, power saving, load balancing, etc. Status information and
resource metrics need to be shared between nodes for dynamic
adjustment of resources and for monitoring purposes. While this
might be achieved by existing protocols when they are available, the
new protocol needs to be able to support parameter exchange,
including mutual synchronization, even when no negotiation as such is
required. In general, these parameters do not apply to all
participating nodes, but only to a subset.
SN1. A basic requirement for the protocol is therefore the ability
to represent, discover, synchronize and negotiate almost any kind of
network parameter among selected subsets of participating nodes.
SN2. Negotiation is an iterative request/response process that must
be guaranteed to terminate (with success or failure). While tie-
breaking rules must be defined specifically for each use case, the
protocol should have some general mechanisms in support of loop and
deadlock prevention, such as hop count limits or timeouts.
SN3. Synchronization must be possible for groups of nodes ranging
from small to very large.
SN4. To avoid "reinventing the wheel", the protocol should be able
to encapsulate the data formats used by existing configuration
protocols (such as NETCONF/YANG) in cases where that is convenient.
SN5. Human intervention in complex situations is costly and error-
prone. Therefore, synchronization or negotiation of parameters
without human intervention is desirable whenever the coordination of
multiple devices can improve overall network performance. It follows
that the protocol's resource requirements must be small enough to fit
in any device that would otherwise need human intervention. The
issue of running in constrained nodes is discussed in
[I-D.ietf-anima-reference-model].
SN6. Human intervention in large networks is often replaced by use
of a top-down network management system (NMS). It therefore follows
that the protocol, as part of the Autonomic Networking
Infrastructure, should be capable of running in any device that would
otherwise be managed by an NMS, and that it can co-exist with an NMS,
and with protocols such as SNMP and NETCONF.
SN7. Specific autonomic features are expected to be implemented by
individual ASAs, but the protocol must be general enough to allow
them. Some examples follow:
o Dependencies and conflicts: In order to decide upon a
configuration for a given device, the device may need information
from neighbors. This can be established through the negotiation
procedure, or through synchronization if that is sufficient.
However, a given item in a neighbor may depend on other
information from its own neighbors, which may need another
negotiation or synchronization procedure to obtain or decide.
Therefore, there are potential dependencies and conflicts among
negotiation or synchronization procedures. Resolving dependencies
and conflicts is a matter for the individual ASAs involved. To
allow this, there need to be clear boundaries and convergence
mechanisms for negotiations. Also some mechanisms are needed to
avoid loop dependencies or uncontrolled growth in a tree of
dependencies. It is the ASA designer's responsibility to avoid or
detect looping dependencies or excessive growth of dependency
trees. The protocol's role is limited to bilateral signaling
between ASAs, and the avoidance of loops during bilateral
signaling.
o Recovery from faults and identification of faulty devices should
be as automatic as possible. The protocol's role is limited to
discovery, synchronization and negotiation. These processes can
occur at any time, and an ASA may need to repeat any of these
steps when the ASA detects an event such as a negotiation
counterpart failing.
o Since a major goal is to minimize human intervention, it is
necessary that the network can in effect "think ahead" before
changing its parameters. One aspect of this is an ASA that relies
on a knowledge base to predict network behavior. This is out of
scope for the signaling protocol. However, another aspect is
forecasting the effect of a change by a "dry run" negotiation
before actually installing the change. Signaling a dry run is
therefore a desirable feature of the protocol.
Note that management logging, monitoring, alerts and tools for
intervention are required. However, these can only be features of
individual ASAs, not of the protocol itself. Another document
[I-D.ietf-anima-stable-connectivity] discusses how such agents may be
linked into conventional OAM systems via an Autonomic Control Plane
[I-D.ietf-anima-autonomic-control-plane].
SN8. The protocol will be able to deal with a wide variety of
technical objectives, covering any type of network parameter.
Therefore the protocol will need a flexible and easily extensible
format for describing objectives. At a later stage it may be
desirable to adopt an explicit information model. One consideration
is whether to adopt an existing information model or to design a new
one.
E.3. Specific Technical Requirements
T1. It should be convenient for ASA designers to define new
technical objectives and for programmers to express them, without
excessive impact on run-time efficiency and footprint. In
particular, it should be convenient for ASAs to be implemented
independently of each other as user space programs rather than as
kernel code, where such a programming model is possible. The classes
of device in which the protocol might run is discussed in
[I-D.ietf-anima-reference-model].
T2. The protocol should be easily extensible in case the initially
defined discovery, synchronization and negotiation mechanisms prove
to be insufficient.
T3. To be a generic platform, the protocol payload format should be
independent of the transport protocol or IP version. In particular,
it should be able to run over IPv6 or IPv4. However, some functions,
such as multicasting on a link, might need to be IP version
dependent. By default, IPv6 should be preferred.
T4. The protocol must be able to access off-link counterparts via
routable addresses, i.e., must not be restricted to link-local
operation.
T5. It must also be possible for an external discovery mechanism to
be used, if appropriate for a given technical objective. In other
words, GRASP discovery must not be a prerequisite for GRASP
negotiation or synchronization.
T6. The protocol must be capable of distinguishing multiple
simultaneous operations with one or more peers, especially when wait
states occur.
T7. Intent: Although the distribution of Intent is out of scope for
this document, the protocol must not by design exclude its use for
Intent distribution.
T8. Management monitoring, alerts and intervention: Devices should
be able to report to a monitoring system. Some events must be able
to generate operator alerts and some provision for emergency
intervention must be possible (e.g. to freeze synchronization or
negotiation in a mis-behaving device). These features might not use
the signaling protocol itself, but its design should not exclude such
use.
T9. Because this protocol may directly cause changes to device
configurations and have significant impacts on a running network, all
protocol exchanges need to be fully secured against forged messages
and man-in-the middle attacks, and secured as much as reasonably
possible against denial of service attacks. There must also be an
encryption mechanism to resist unwanted monitoring. However, it is
not required that the protocol itself provides these security
features; it may depend on an existing secure environment.
Appendix F. Capability Analysis of Current Protocols
This appendix discusses various existing protocols with properties This appendix discusses various existing protocols with properties
related to the requirements described in Section 2. The purpose is related to the requirements described in Appendix E. The purpose is
to evaluate whether any existing protocol, or a simple combination of to evaluate whether any existing protocol, or a simple combination of
existing protocols, can meet those requirements. existing protocols, can meet those requirements.
Numerous protocols include some form of discovery, but these all Numerous protocols include some form of discovery, but these all
appear to be very specific in their applicability. Service Location appear to be very specific in their applicability. Service Location
Protocol (SLP) [RFC2608] provides service discovery for managed Protocol (SLP) [RFC2608] provides service discovery for managed
networks, but requires configuration of its own servers. DNS-SD networks, but requires configuration of its own servers. DNS-SD
[RFC6763] combined with mDNS [RFC6762] provides service discovery for [RFC6763] combined with mDNS [RFC6762] provides service discovery for
small networks with a single link layer. [RFC7558] aims to extend small networks with a single link layer. [RFC7558] aims to extend
this to larger autonomous networks but this is not yet standardized. this to larger autonomous networks but this is not yet standardized.
However, both SLP and DNS-SD appear to target primarily application However, both SLP and DNS-SD appear to target primarily application
layer services, not the layer 2 and 3 objectives relevant to basic layer services, not the layer 2 and 3 objectives relevant to basic
network configuration. Both SLP and DNS-SD are text-based protocols. network configuration. Both SLP and DNS-SD are text-based protocols.
Routing protocols are mainly one-way information announcements. The
receiver makes independent decisions based on the received
information and there is no direct feedback information to the
announcing peer. This remains true even though the protocol is used
in both directions between peer routers; there is state
synchronization, but no negotiation, and each peer runs its route
calculations independently.
Simple Network Management Protocol (SNMP) [RFC3416] uses a command/ Simple Network Management Protocol (SNMP) [RFC3416] uses a command/
response model not well suited for peer negotiation. Network response model not well suited for peer negotiation. Network
Configuration Protocol (NETCONF) [RFC6241] uses an RPC model that Configuration Protocol (NETCONF) [RFC6241] uses an RPC model that
does allow positive or negative responses from the target system, but does allow positive or negative responses from the target system, but
this is still not adequate for negotiation. this is still not adequate for negotiation.
There are various existing protocols that have elementary negotiation There are various existing protocols that have elementary negotiation
abilities, such as Dynamic Host Configuration Protocol for IPv6 abilities, such as Dynamic Host Configuration Protocol for IPv6
(DHCPv6) [RFC3315], Neighbor Discovery (ND) [RFC4861], Port Control (DHCPv6) [RFC3315], Neighbor Discovery (ND) [RFC4861], Port Control
Protocol (PCP) [RFC6887], Remote Authentication Dial In User Service Protocol (PCP) [RFC6887], Remote Authentication Dial In User Service
(RADIUS) [RFC2865], Diameter [RFC6733], etc. Most of them are (RADIUS) [RFC2865], Diameter [RFC6733], etc. Most of them are
configuration or management protocols. However, they either provide configuration or management protocols. However, they either provide
only a simple request/response model in a master/slave context or only a simple request/response model in a master/slave context or
very limited negotiation abilities. very limited negotiation abilities.
There are some signaling protocols with an element of negotiation. There are some signaling protocols with an element of negotiation.
For example Resource ReSerVation Protocol (RSVP) [RFC2205] was For example Resource ReSerVation Protocol (RSVP) [RFC2205] was
designed for negotiating quality of service parameters along the path designed for negotiating quality of service parameters along the path
of a unicast or multicast flow. RSVP is a very specialised protocol of a unicast or multicast flow. RSVP is a very specialised protocol
aimed at end-to-end flows. However, it has some flexibility, having aimed at end-to-end flows. A more generic design is General Internet
been extended for MPLS label distribution [RFC3209]. A more generic Signalling Transport (GIST) [RFC5971], but it is complex, tries to
design is General Internet Signalling Transport (GIST) [RFC5971], but solve many problems, and is also aimed at per-flow signaling across
it is complex, tries to solve many problems, and is also aimed at many hops rather than at device-to-device signaling. However, we
per-flow signaling across many hops rather than at device-to-device cannot completely exclude extended RSVP or GIST as a synchronization
signaling. However, we cannot completely exclude extended RSVP or and negotiation protocol. They do not appear to be directly useable
GIST as a synchronization and negotiation protocol. They do not for peer discovery.
appear to be directly useable for peer discovery.
RESTCONF [RFC8040] is a protocol intended to convey NETCONF RESTCONF [RFC8040] is a protocol intended to convey NETCONF
information expressed in the YANG language via HTTP, including the information expressed in the YANG language via HTTP, including the
ability to transit HTML intermediaries. While this is a powerful ability to transit HTML intermediaries. While this is a powerful
approach in the context of centralised configuration of a complex approach in the context of centralised configuration of a complex
network, it is not well adapted to efficient interactive negotiation network, it is not well adapted to efficient interactive negotiation
between peer devices, especially simple ones that might not include between peer devices, especially simple ones that might not include
YANG processing already. YANG processing already.
The Distributed Node Consensus Protocol (DNCP) [RFC7787] is defined The Distributed Node Consensus Protocol (DNCP) [RFC7787] is defined
skipping to change at page 77, line 37 skipping to change at page 78, line 33
information exchange and negotiation but not directly at peer information exchange and negotiation but not directly at peer
discovery. However, it has many points in common with the present discovery. However, it has many points in common with the present
work. work.
None of the above solutions appears to completely meet the needs of None of the above solutions appears to completely meet the needs of
generic discovery, state synchronization and negotiation in a single generic discovery, state synchronization and negotiation in a single
solution. Many of the protocols assume that they are working in a solution. Many of the protocols assume that they are working in a
traditional top-down or north-south scenario, rather than a fluid traditional top-down or north-south scenario, rather than a fluid
peer-to-peer scenario. Most of them are specialized in one way or peer-to-peer scenario. Most of them are specialized in one way or
another. As a result, we have not identified a combination of another. As a result, we have not identified a combination of
existing protocols that meets the requirements in Section 2. Also, existing protocols that meets the requirements in Appendix E. Also,
we have not identified a path by which one of the existing protocols we have not identified a path by which one of the existing protocols
could be extended to meet the requirements. could be extended to meet the requirements.
Authors' Addresses Authors' Addresses
Carsten Bormann Carsten Bormann
Universitaet Bremen TZI Universitaet Bremen TZI
Postfach 330440 Postfach 330440
D-28359 Bremen D-28359 Bremen
Germany Germany
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