draft-ietf-anima-grasp-09.txt   draft-ietf-anima-grasp-10.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: June 18, 2017 Univ. of Auckland Expires: September 11, 2017 Univ. of Auckland
B. Liu, Ed. B. Liu, Ed.
Huawei Technologies Co., Ltd Huawei Technologies Co., Ltd
December 15, 2016 March 10, 2017
A Generic Autonomic Signaling Protocol (GRASP) A Generic Autonomic Signaling Protocol (GRASP)
draft-ietf-anima-grasp-09 draft-ietf-anima-grasp-10
Abstract Abstract
This document establishes requirements for a signaling protocol that This document establishes requirements for a signaling protocol that
enables autonomic devices and autonomic service agents to dynamically enables autonomic nodes and autonomic service agents to dynamically
discover peers, to synchronize state with them, and to negotiate discover peers, to synchronize state with them, and to negotiate
parameter settings mutually with them. The document then defines a parameter settings with them. The document then defines a general
general protocol for discovery, synchronization and negotiation, protocol for discovery, synchronization and negotiation, while the
while the technical objectives for specific scenarios are to be technical objectives for specific scenarios are to be described in
described in separate documents. An Appendix briefly discusses separate documents. An Appendix briefly discusses existing protocols
existing protocols with comparable features. with comparable features.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 18, 2017. This Internet-Draft will expire on September 11, 2017.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirement Analysis of Discovery, Synchronization and 2. Requirement Analysis of Discovery, Synchronization and
Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . 4 Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements for Discovery . . . . . . . . . . . . . . . 5 2.1. Requirements for Discovery . . . . . . . . . . . . . . . 5
2.2. Requirements for Synchronization and Negotiation 2.2. Requirements for Synchronization and Negotiation
Capability . . . . . . . . . . . . . . . . . . . . . . . 6 Capability . . . . . . . . . . . . . . . . . . . . . . . 6
2.3. Specific Technical Requirements . . . . . . . . . . . . . 9 2.3. Specific Technical Requirements . . . . . . . . . . . . . 9
3. GRASP Protocol Overview . . . . . . . . . . . . . . . . . . . 10 3. GRASP Protocol Overview . . . . . . . . . . . . . . . . . . . 10
3.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 10 3.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 10
3.2. High Level Deployment Model . . . . . . . . . . . . . . . 12 3.2. High Level Deployment Model . . . . . . . . . . . . . . . 12
3.3. High Level Design Choices . . . . . . . . . . . . . . . . 13 3.3. High Level Design Choices . . . . . . . . . . . . . . . . 13
3.4. Quick Operating Overview . . . . . . . . . . . . . . . . 16 3.4. Quick Operating Overview . . . . . . . . . . . . . . . . 16
3.5. GRASP Protocol Basic Properties and Mechanisms . . . . . 16 3.5. GRASP Protocol Basic Properties and Mechanisms . . . . . 16
3.5.1. Required External Security Mechanism . . . . . . . . 16 3.5.1. Required External Security Mechanism . . . . . . . . 16
3.5.2. Constrained Instances . . . . . . . . . . . . . . . . 17 3.5.2. Constrained Instances . . . . . . . . . . . . . . . . 17
3.5.3. Transport Layer Usage . . . . . . . . . . . . . . . . 19 3.5.3. Transport Layer Usage . . . . . . . . . . . . . . . . 19
3.5.4. Discovery Mechanism and Procedures . . . . . . . . . 20 3.5.4. Discovery Mechanism and Procedures . . . . . . . . . 20
3.5.5. Negotiation Procedures . . . . . . . . . . . . . . . 23 3.5.5. Negotiation Procedures . . . . . . . . . . . . . . . 23
3.5.6. Synchronization and Flooding Procedure . . . . . . . 25 3.5.6. Synchronization and Flooding Procedures . . . . . . . 25
3.6. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 27 3.6. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 27
3.7. Session Identifier (Session ID) . . . . . . . . . . . . . 27 3.7. Session Identifier (Session ID) . . . . . . . . . . . . . 28
3.8. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 28 3.8. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 29
3.8.1. Message Overview . . . . . . . . . . . . . . . . . . 28 3.8.1. Message Overview . . . . . . . . . . . . . . . . . . 29
3.8.2. GRASP Message Format . . . . . . . . . . . . . . . . 29 3.8.2. GRASP Message Format . . . . . . . . . . . . . . . . 29
3.8.3. Message Size . . . . . . . . . . . . . . . . . . . . 29 3.8.3. Message Size . . . . . . . . . . . . . . . . . . . . 30
3.8.4. Discovery Message . . . . . . . . . . . . . . . . . . 30 3.8.4. Discovery Message . . . . . . . . . . . . . . . . . . 30
3.8.5. Discovery Response Message . . . . . . . . . . . . . 31 3.8.5. Discovery Response Message . . . . . . . . . . . . . 31
3.8.6. Request Messages . . . . . . . . . . . . . . . . . . 32 3.8.6. Request Messages . . . . . . . . . . . . . . . . . . 32
3.8.7. Negotiation Message . . . . . . . . . . . . . . . . . 33 3.8.7. Negotiation Message . . . . . . . . . . . . . . . . . 33
3.8.8. Negotiation End Message . . . . . . . . . . . . . . . 33 3.8.8. Negotiation End Message . . . . . . . . . . . . . . . 34
3.8.9. Confirm Waiting Message . . . . . . . . . . . . . 33 3.8.9. Confirm Waiting Message . . . . . . . . . . . . . 34
3.8.10. Synchronization Message . . . . . . . . . . . . . . . 34 3.8.10. Synchronization Message . . . . . . . . . . . . . . . 34
3.8.11. Flood Synchronization Message . . . . . . . . . . . . 34 3.8.11. Flood Synchronization Message . . . . . . . . . . . . 35
3.8.12. Invalid Message . . . . . . . . . . . . . . . . . . . 35 3.8.12. Invalid Message . . . . . . . . . . . . . . . . . . . 36
3.8.13. No Operation Message . . . . . . . . . . . . . . . . 35 3.8.13. No Operation Message . . . . . . . . . . . . . . . . 36
3.9. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 36 3.9. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 36
3.9.1. Format of GRASP Options . . . . . . . . . . . . . . . 36 3.9.1. Format of GRASP Options . . . . . . . . . . . . . . . 36
3.9.2. Divert Option . . . . . . . . . . . . . . . . . . . . 36 3.9.2. Divert Option . . . . . . . . . . . . . . . . . . . . 37
3.9.3. Accept Option . . . . . . . . . . . . . . . . . . . . 36 3.9.3. Accept Option . . . . . . . . . . . . . . . . . . . . 37
3.9.4. Decline Option . . . . . . . . . . . . . . . . . . . 37 3.9.4. Decline Option . . . . . . . . . . . . . . . . . . . 37
3.9.5. Locator Options . . . . . . . . . . . . . . . . . . . 37 3.9.5. Locator Options . . . . . . . . . . . . . . . . . . . 38
3.10. Objective Options . . . . . . . . . . . . . . . . . . . . 39 3.10. Objective Options . . . . . . . . . . . . . . . . . . . . 40
3.10.1. Format of Objective Options . . . . . . . . . . . . 39 3.10.1. Format of Objective Options . . . . . . . . . . . . 40
3.10.2. Objective flags . . . . . . . . . . . . . . . . . . 40 3.10.2. Objective flags . . . . . . . . . . . . . . . . . . 41
3.10.3. General Considerations for Objective Options . . . . 41 3.10.3. General Considerations for Objective Options . . . . 41
3.10.4. Organizing of Objective Options . . . . . . . . . . 41 3.10.4. Organizing of Objective Options . . . . . . . . . . 42
3.10.5. Experimental and Example Objective Options . . . . . 43 3.10.5. Experimental and Example Objective Options . . . . . 43
4. Implementation Status [RFC Editor: please remove] . . . . . . 43 4. Implementation Status [RFC Editor: please remove] . . . . . . 44
4.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 43 4.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 44
4.2. Python Implementation . . . . . . . . . . . . . . . . . . 44 4.2. Python Implementation . . . . . . . . . . . . . . . . . . 44
5. Security Considerations . . . . . . . . . . . . . . . . . . . 45 5. Security Considerations . . . . . . . . . . . . . . . . . . . 45
6. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 47 6. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 47
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 51 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 52
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 51 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
9.1. Normative References . . . . . . . . . . . . . . . . . . 51 9.1. Normative References . . . . . . . . . . . . . . . . . . 52
9.2. Informative References . . . . . . . . . . . . . . . . . 52 9.2. Informative References . . . . . . . . . . . . . . . . . 53
Appendix A. Open Issues [RFC Editor: Please remove if empty] . . 55 Appendix A. Open Issues [RFC Editor: This section should be
Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 55 empty. Please remove] . . . . . . . . . . . . . . . 56
Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 63 Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 57
Appendix D. Example Message Formats . . . . . . . . . . . . . . 69 Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 65
D.1. Discovery Example . . . . . . . . . . . . . . . . . . . . 69 Appendix D. Example Message Formats . . . . . . . . . . . . . . 71
D.2. Flood Example . . . . . . . . . . . . . . . . . . . . . . 70 D.1. Discovery Example . . . . . . . . . . . . . . . . . . . . 71
D.3. Synchronization Example . . . . . . . . . . . . . . . . . 70 D.2. Flood Example . . . . . . . . . . . . . . . . . . . . . . 72
D.4. Simple Negotiation Example . . . . . . . . . . . . . . . 70 D.3. Synchronization Example . . . . . . . . . . . . . . . . . 72
D.5. Complete Negotiation Example . . . . . . . . . . . . . . 71 D.4. Simple Negotiation Example . . . . . . . . . . . . . . . 72
Appendix E. Capability Analysis of Current Protocols . . . . . . 72 D.5. Complete Negotiation Example . . . . . . . . . . . . . . 73
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 75 Appendix E. Capability Analysis of Current Protocols . . . . . . 74
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 76
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].
One approach is to largely decentralize the logic of network One approach is to largely decentralize the logic of network
management by migrating it into network elements. A reference model management by migrating it into network elements. A reference model
for autonomic networking on this basis is given in for autonomic networking on this basis is given in
[I-D.ietf-anima-reference-model]. The reader should consult this [I-D.ietf-anima-reference-model]. The reader should consult this
document to understand how various autonomic components fit together. document to understand how various autonomic components fit together.
In order to fulfil 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 3.1).
skipping to change at page 4, line 23 skipping to change at page 4, line 24
Following this Introduction, Section 2 describes the requirements for Following this Introduction, Section 2 describes the requirements for
discovery, synchronization and negotiation. Negotiation is an discovery, synchronization and negotiation. Negotiation is an
iterative process, requiring multiple message exchanges forming a iterative process, requiring multiple message exchanges forming a
closed loop between the negotiating entities. In fact, these closed loop between the negotiating entities. In fact, these
entities are ASAs, normally but not necessarily in different network entities are ASAs, normally but not necessarily in different network
devices. State synchronization, when needed, can be regarded as a devices. State synchronization, when needed, can be regarded as a
special case of negotiation, without iteration. Section 3.3 special case of negotiation, without iteration. Section 3.3
describes a behavior model for a protocol intended to support describes a behavior model for a protocol intended to support
discovery, synchronization and negotiation. The design of GeneRic discovery, synchronization and negotiation. The design of GeneRic
Autonomic Signaling Protocol (GRASP) in Section 3 of this document is Autonomic Signaling Protocol (GRASP) in Section 3 of this document is
mainly based on this behavior model. The relevant capabilities of based on this behavior model. The relevant capabilities of various
various existing protocols are reviewed in Appendix E. existing protocols are reviewed in Appendix E.
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, but also supports diversion to off-link peers. There is no process on the local link, but also supports diversion to peers on
assumption of any particular form of network topology. When a device other links. There is no assumption of any particular form of
starts up with no pre-configuration, it has no knowledge of the network topology. When a device starts up with no pre-configuration,
topology. The protocol itself is capable of being used in a small it has no knowledge of the topology. The protocol itself is capable
and/or flat network structure such as a small office or home network of being used in a small and/or flat network structure such as a
as well as a professionally managed network. Therefore, the small office or home network as well as in a large professionally
discovery mechanism needs to be able to allow a device to bootstrap managed network. Therefore, the discovery mechanism needs to be able
itself without making any prior assumptions about network structure. to allow a device to bootstrap itself without making any prior
assumptions about network structure.
Because GRASP can be used to perform 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.
It is understood that in realistic deployments, not all devices will In realistic deployments, not all devices will support GRASP.
support GRASP. It is expected that some autonomic service agents Therefore, some autonomic service agents will directly manage a group
will directly manage a group of non-autonomic nodes, and that other of non-autonomic nodes, and other non-autonomic nodes will be managed
non-autonomic nodes will be managed traditionally. Such mixed traditionally. Such mixed scenarios are not discussed in this
scenarios are not discussed in this specification. specification.
2. Requirement Analysis of Discovery, Synchronization and Negotiation 2. Requirement Analysis of Discovery, Synchronization and Negotiation
This section discusses the requirements for discovery, negotiation This section discusses the requirements for discovery, negotiation
and synchronization capabilities. The primary user of the protocol and synchronization capabilities. The primary user of the protocol
is an autonomic service agent (ASA), so the requirements are mainly is an autonomic service agent (ASA), so the requirements are mainly
expressed as the features needed by an ASA. A single physical device expressed as the features needed by an ASA. A single physical device
might contain several ASAs, and a single ASA might manage several might contain several ASAs, and a single ASA might manage several
technical objectives. If a technical objective is managed by several technical objectives. If a technical objective is managed by several
ASAs, any necessary coordination is outside the scope of the ASAs, any necessary coordination is outside the scope of the GRASP
signaling protocol itself. signaling protocol. Furthermore, requirements for ASAs themselves,
such as the processing of Intent [RFC7575], are out of scope for the
Note that requirements for ASAs themselves, such as the processing of present document.
Intent [RFC7575] or interfaces for coordination between ASAs are out
of scope for the present document.
2.1. Requirements for Discovery 2.1. Requirements for Discovery
D1. ASAs may be designed to manage anything, as required in D1. ASAs may be designed to manage any type of configurable device
Section 2.2. A basic requirement is therefore that the protocol can or software, as required in Section 2.2. A basic requirement is
represent and discover any kind of technical objective among therefore that the protocol can represent and discover any kind of
arbitrary subsets of participating nodes. technical objective among arbitrary subsets of participating nodes.
In an autonomic network we must assume that when a device starts up In an autonomic network we must assume that when a device starts up
it has no information about any peer devices, the network structure, 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 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 in the same situation. In some cases, when a new application session
starts up within a device, the device or ASA may again lack starts up within a device, the device or ASA may again lack
information about relevant peers. For example, it might be necessary information about relevant peers. For example, it might be necessary
to set up resources on multiple other devices, coordinated and to set up resources on multiple other devices, coordinated and
matched to each other so that there is no wasted resource. Security matched to each other so that there is no wasted resource. Security
settings might also need updating to allow for the new device or settings might also need updating to allow for the new device or
user. The relevant peers may be different for different technical user. The relevant peers may be different for different technical
objectives. Therefore discovery needs to be repeated as often as objectives. Therefore discovery needs to be repeated as often as
necessary to find peers capable of acting as counterparts for each necessary to find peers capable of acting as counterparts for each
objective that a discovery initiator needs to handle. From this objective that a discovery initiator needs to handle. From this
background we derive the next three requirements: background we derive the next three requirements:
D2. When an ASA first starts up, it has no knowledge of the specific D2. When an ASA first starts up, it may have no knowledge of the
network to which it is attached. Therefore the discovery process specific network to which it is attached. Therefore the discovery
must be able to support any network scenario, assuming only that the process must be able to support any network scenario, assuming only
device concerned is bootstrapped from factory condition. that the device concerned is bootstrapped from factory condition.
D3. When an ASA starts up, it must require no configured location D3. When an ASA starts up, it must require no configured location
information about any peers in order to discover them. information about any peers in order to discover them.
D4. If an ASA supports multiple technical objectives, relevant peers D4. If an ASA supports multiple technical objectives, relevant peers
may be different for different discovery objectives, so discovery may be different for different discovery objectives, so discovery
needs to be performed separately to find counterparts for each needs to be performed separately to find counterparts for each
objective. Thus, there must be a mechanism by which an ASA can objective. Thus, there must be a mechanism by which an ASA can
separately discover peer ASAs for each of the technical objectives separately discover peer ASAs for each of the technical objectives
that it needs to manage, whenever necessary. that it needs to manage, whenever necessary.
D5. Following discovery, an ASA will normally perform negotiation or D5. Following discovery, an ASA will normally perform negotiation or
synchronization for the corresponding objectives. The design should synchronization for the corresponding objectives. The design should
allow for this by conveniently linking discovery to negotiation and allow for this by conveniently linking discovery to negotiation and
synchronization. It may provide an optional mechanism to combine synchronization. It may provide an optional mechanism to combine
discovery and negotiation/synchronization in a single call. discovery and negotiation/synchronization in a single protocol
exchange.
D6. Some objectives may only be significant on the local link, but D6. Some objectives may only be significant on the local link, but
others may be significant across the routed network and require off- others may be significant across the routed network and require off-
link operations. Thus, the relevant peers might be immediate link operations. Thus, the relevant peers might be immediate
neighbors on the same layer 2 link, or they might be more distant and neighbors on the same layer 2 link, or they might be more distant and
only accessible via layer 3. The mechanism must therefore provide only accessible via layer 3. The mechanism must therefore provide
both on-link and off-link discovery of ASAs supporting specific both on-link and off-link discovery of ASAs supporting specific
technical objectives. technical objectives.
D7. The discovery process should be flexible enough to allow for D7. The discovery process should be flexible enough to allow for
special cases, such as the following: special cases, such as the following:
o During initialisation, a device must be able to establish mutual o During initialization, a device must be able to establish mutual
trust with the rest of the network and join an authentication trust with the rest of the network and participate in an
mechanism. Although this will inevitably start with a discovery authentication mechanism. Although this will inevitably start
action, it is a special case precisely because trust is not yet with a discovery action, it is a special case precisely because
established. This topic is the subject of trust is not yet established. This topic is the subject of
[I-D.ietf-anima-bootstrapping-keyinfra]. We require that once [I-D.ietf-anima-bootstrapping-keyinfra]. We require that once
trust has been established for a device, all ASAs within the trust has been established for a device, all ASAs within the
device inherit the device's credentials and are also trusted. 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 o Depending on the type of network involved, discovery of other
central functions might be needed, such as the Network Operations central functions might be needed, such as the Network Operations
Center (NOC) [I-D.ietf-anima-stable-connectivity]. The protocol Center (NOC) [I-D.ietf-anima-stable-connectivity]. The protocol
must be capable of supporting such discovery during must be capable of supporting such discovery during
initialisation, as well as discovery during ongoing operation. initialization, as well as discovery during ongoing operation.
D8. The discovery process must not generate excessive traffic and D8. The discovery process must not generate excessive traffic and
must take account of sleeping nodes. must take account of sleeping nodes.
D9. There must be a mechanism for handling stale discovery results. D9. There must be a mechanism for handling stale discovery results.
2.2. Requirements for Synchronization and Negotiation Capability 2.2. Requirements for Synchronization and Negotiation Capability
As background, consider the example of routing protocols, the closest As background, consider the example of routing protocols, the closest
approximation to autonomic networking already in widespread use. approximation to autonomic networking already in widespread use.
Routing protocols use a largely autonomic model based on distributed Routing protocols use a largely autonomic model based on distributed
devices that communicate repeatedly with each other. The focus is devices that communicate repeatedly with each other. The focus is
reachability, so current routing protocols mainly consider simple reachability, so routing protocols primarily consider simple link
link status, i.e., up or down, and an underlying assumption is that status and metrics, and an underlying assumption is that nodes need a
all nodes need a consistent view of the network topology in order for consistent, although partial, view of the network topology in order
the routing algorithm to converge. Thus, routing is mainly based on for the routing algorithm to converge. Also, routing is mainly based
information synchronization between peers, rather than on bi- on simple information synchronization between peers, rather than on
directional negotiation. Other information, such as latency, bi-directional negotiation.
congestion, capacity, and particularly unused capacity, would be
helpful to get better path selection and utilization rate, but is not By contrast, autonomic networks need to be able to manage many
normally used in distributed routing algorithms. Additionally, different types of parameter and consider many more dimensions, such
autonomic networks need to be able to manage many more dimensions, as latency, load, unused or limited resources, conflicting resource
such as security settings, power saving, load balancing, etc. Status requests, security settings, power saving, load balancing, etc.
information and traffic metrics need to be shared between nodes for Status information and resource metrics need to be shared between
dynamic adjustment of resources and for monitoring purposes. While nodes for dynamic adjustment of resources and for monitoring
this might be achieved by existing protocols when they are available, purposes. While this might be achieved by existing protocols when
the new protocol needs to be able to support parameter exchange, they are available, the new protocol needs to be able to support
including mutual synchronization, even when no negotiation as such is parameter exchange, including mutual synchronization, even when no
required. In general, these parameters do not apply to all negotiation as such is required. In general, these parameters do not
participating nodes, but only to a subset. apply to all participating nodes, but only to a subset.
SN1. A basic requirement for the protocol is therefore the ability SN1. A basic requirement for the protocol is therefore the ability
to represent, discover, synchronize and negotiate almost any kind of to represent, discover, synchronize and negotiate almost any kind of
network parameter among selected subsets of participating nodes. network parameter among selected subsets of participating nodes.
SN2. Negotiation is a request/response process that must be SN2. Negotiation is an iterative request/response process that must
guaranteed to terminate (with success or failure) and if necessary it be guaranteed to terminate (with success or failure). While tie-
must contain tie-breaking rules for each technical objective that breaking rules must be defined specifically for each use case, the
requires them. While these must be defined specifically for each use protocol should have some general mechanisms in support of loop and
case, the protocol should have some general mechanisms in support of deadlock prevention, such as hop count limits or timeouts.
loop and deadlock prevention, such as hop count limits or timeouts.
SN3. Synchronization might concern small groups of nodes or very SN3. Synchronization must be possible for groups of nodes ranging
large groups. Different solutions might be needed at different from small to very large.
scales.
SN4. To avoid "reinventing the wheel", the protocol should be able SN4. To avoid "reinventing the wheel", the protocol should be able
to encapsulate the data formats used by existing configuration to encapsulate the data formats used by existing configuration
protocols (such as NETCONF/YANG) in cases where that is convenient. protocols (such as NETCONF/YANG) in cases where that is convenient.
SN5. Human intervention in complex situations is costly and error- SN5. Human intervention in complex situations is costly and error-
prone. Therefore, synchronization or negotiation of parameters prone. Therefore, synchronization or negotiation of parameters
without human intervention is desirable whenever the coordination of without human intervention is desirable whenever the coordination of
multiple devices can improve overall network performance. It multiple devices can improve overall network performance. It follows
therefore follows that the protocol, as part of the Autonomic that the protocol's resource requirements must be appropriate for any
Networking Infrastructure, should be capable of running in any device device that would otherwise need human intervention. The issue of
that would otherwise need human intervention. The issue of running running in constrained nodes is discussed in
in constrained nodes is discussed in
[I-D.ietf-anima-reference-model]. [I-D.ietf-anima-reference-model].
SN6. Human intervention in large networks is often replaced by use SN6. Human intervention in large networks is often replaced by use
of a top-down network management system (NMS). It therefore follows of a top-down network management system (NMS). It therefore follows
that the protocol, as part of the Autonomic Networking that the protocol, as part of the Autonomic Networking
Infrastructure, should be capable of running in any device that would 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, otherwise be managed by an NMS, and that it can co-exist with an NMS,
and with protocols such as SNMP and NETCONF. and with protocols such as SNMP and NETCONF.
SN7. Some features are expected to be implemented by individual SN7. Some features are expected to be implemented by individual
skipping to change at page 8, line 22 skipping to change at page 8, line 23
from neighbors. This can be established through the negotiation from neighbors. This can be established through the negotiation
procedure, or through synchronization if that is sufficient. procedure, or through synchronization if that is sufficient.
However, a given item in a neighbor may depend on other However, a given item in a neighbor may depend on other
information from its own neighbors, which may need another information from its own neighbors, which may need another
negotiation or synchronization procedure to obtain or decide. negotiation or synchronization procedure to obtain or decide.
Therefore, there are potential dependencies and conflicts among Therefore, there are potential dependencies and conflicts among
negotiation or synchronization procedures. Resolving dependencies negotiation or synchronization procedures. Resolving dependencies
and conflicts is a matter for the individual ASAs involved. To and conflicts is a matter for the individual ASAs involved. To
allow this, there need to be clear boundaries and convergence allow this, there need to be clear boundaries and convergence
mechanisms for negotiations. Also some mechanisms are needed to mechanisms for negotiations. Also some mechanisms are needed to
avoid loop dependencies. In such a case, the protocol's role is avoid loop dependencies or uncontrolled growth in a tree of
limited to bilateral signaling between ASAs. 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 o Recovery from faults and identification of faulty devices should
be as automatic as possible. The protocol's role is limited to be as automatic as possible. The protocol's role is limited to
discovery, synchronization and negotiation. These processes can discovery, synchronization and negotiation. These processes can
occur at any time, and an ASA may need to repeat any of these occur at any time, and an ASA may need to repeat any of these
steps when the ASA detects an anomaly such as a negotiation steps when the ASA detects an event such as a negotiation
counterpart failing. counterpart failing.
o Since the goal is to minimize human intervention, it is necessary o Since a major goal is to minimize human intervention, it is
that the network can in effect "think ahead" before changing its necessary that the network can in effect "think ahead" before
parameters. One aspect of this is an ASA that relies on a changing its parameters. One aspect of this is an ASA that relies
knowledge base to predict network behavior. This is out of scope on a knowledge base to predict network behavior. This is out of
for the signaling protocol. However, another aspect is scope for the signaling protocol. However, another aspect is
forecasting the effect of a change by a "dry run" negotiation forecasting the effect of a change by a "dry run" negotiation
before actually installing the change. This will be an before actually installing the change. Signaling a dry run is
application of the protocol rather than a feature of the protocol therefore a desirable feature of the protocol.
itself.
o Management logging, monitoring, alerts and tools for intervention Note that management logging, monitoring, alerts and tools for
are required. However, these can only be features of individual intervention are required. However, these can only be features of
ASAs. Another document [I-D.ietf-anima-stable-connectivity] individual ASAs, not of the protocol itself. Another document
discusses how such agents may be linked into conventional OAM [I-D.ietf-anima-stable-connectivity] discusses how such agents may be
systems via an Autonomic Control Plane linked into conventional OAM systems via an Autonomic Control Plane
[I-D.ietf-anima-autonomic-control-plane]. [I-D.ietf-anima-autonomic-control-plane].
SN8. The protocol will be able to deal with a wide variety of SN8. The protocol will be able to deal with a wide variety of
technical objectives, covering any type of network parameter. technical objectives, covering any type of network parameter.
Therefore the protocol will need a flexible and easily extensible Therefore the protocol will need a flexible and easily extensible
format for describing objectives. At a later stage it may be format for describing objectives. At a later stage it may be
desirable to adopt an explicit information model. One consideration desirable to adopt an explicit information model. One consideration
is whether to adopt an existing information model or to design a new is whether to adopt an existing information model or to design a new
one. one.
2.3. Specific Technical Requirements 2.3. Specific Technical Requirements
T1. It should be convenient for ASA designers to define new T1. It should be convenient for ASA designers to define new
technical objectives and for programmers to express them, without technical objectives and for programmers to express them, without
excessive impact on run-time efficiency and footprint. In excessive impact on run-time efficiency and footprint. In
particular, it should be possible for ASAs to be implemented particular, it should be convenient for ASAs to be implemented
independently of each other as user space programs rather than as independently of each other as user space programs rather than as
kernel code. The classes of device in which the protocol might run kernel code, where such a programming model is possible. The classes
is discussed in [I-D.ietf-anima-reference-model]. 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 T2. The protocol should be easily extensible in case the initially
defined discovery, synchronization and negotiation mechanisms prove defined discovery, synchronization and negotiation mechanisms prove
to be insufficient. to be insufficient.
T3. To be a generic platform, the protocol payload format should be T3. To be a generic platform, the protocol payload format should be
independent of the transport protocol or IP version. In particular, independent of the transport protocol or IP version. In particular,
it should be able to run over IPv6 or IPv4. However, some functions, 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 such as multicasting on a link, might need to be IP version
dependent. In case of doubt, IPv6 should be preferred. dependent. By default, IPv6 should be preferred.
T4. The protocol must be able to access off-link counterparts via T4. The protocol must be able to access off-link counterparts via
routable addresses, i.e., must not be restricted to link-local routable addresses, i.e., must not be restricted to link-local
operation. operation.
T5. It must also be possible for an external discovery mechanism to T5. It must also be possible for an external discovery mechanism to
be used, if appropriate for a given technical objective. In other be used, if appropriate for a given technical objective. In other
words, GRASP discovery must not be a prerequisite for GRASP words, GRASP discovery must not be a prerequisite for GRASP
negotiation or synchronization. negotiation or synchronization.
T6. The protocol must be capable of supporting multiple simultaneous T6. The protocol must be capable of supporting multiple simultaneous
operations, especially when wait states occur. operations with one or more peers, especially when wait states occur.
T7. Intent: There must be provision for general Intent rules to be T7. Intent: Although the distribution of Intent is out of scope for
applied by all devices in the network (e.g., security rules, prefix this document, the protocol must not by design exclude its use for
length, resource sharing rules). However, Intent distribution might Intent distribution.
not use the signaling protocol itself, but its design should not
exclude such use.
T8. Management monitoring, alerts and intervention: Devices should T8. Management monitoring, alerts and intervention: Devices should
be able to report to a monitoring system. Some events must be able be able to report to a monitoring system. Some events must be able
to generate operator alerts and some provision for emergency to generate operator alerts and some provision for emergency
intervention must be possible (e.g. to freeze synchronization or intervention must be possible (e.g. to freeze synchronization or
negotiation in a mis-behaving device). These features might not use negotiation in a mis-behaving device). These features might not use
the signaling protocol itself, but its design should not exclude such the signaling protocol itself, but its design should not exclude such
use. use.
T9. The protocol needs to be fully secured against forged messages 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 and man-in-the middle attacks, and secured as much as reasonably
possible against denial of service attacks. It needs to be capable possible against denial of service attacks. There must also be an
of encryption in order to resist unwanted monitoring. However, it is encryption mechanism to resist unwanted monitoring. However, it is
not required that the protocol itself provides these security not required that the protocol itself provides these security
features; it may depend on an existing secure environment. features; it may depend on an existing secure environment.
3. GRASP Protocol Overview 3. GRASP Protocol Overview
3.1. Terminology 3.1. 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].
The following additional terms are used throughout this document: The following additional terms are used throughout this document:
o Autonomic Device: identical to Autonomic Node.
o Discovery: a process by which an ASA discovers peers according to o Discovery: a process by which an ASA discovers peers according to
a specific discovery objective. The discovery results may be a specific discovery objective. The discovery results may be
different according to the different discovery objectives. The different according to the different discovery objectives. The
discovered peers may later be used as negotiation counterparts or discovered peers may later be used as negotiation counterparts or
as sources of synchronization data. as sources of synchronization data.
o Negotiation: a process by which two ASAs interact iteratively to o Negotiation: a process by which two ASAs interact iteratively to
agree on parameter settings that best satisfy the objectives of agree on parameter settings that best satisfy the objectives of
both ASAs. both ASAs.
o State Synchronization: a process by which ASAs interact to receive o State Synchronization: a process by which ASAs interact to receive
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 configurable parameter or set of technical objective is a data structure, whose main contents are a
parameters of some kind, which occurs in three contexts: name and a value. The value consists of a single configurable
parameter or a set of parameters of some kind. The exact format
Discovery, Negotiation and Synchronization. In the protocol, an of an objective is defined in Section 3.10.1. An objective occurs
objective is represented by an identifier and, if relevant, a in three contexts: Discovery, Negotiation and Synchronization.
value. Normally, a given objective will not occur in negotiation Normally, a given objective will not occur in negotiation and
and synchronization contexts simultaneously. synchronization contexts simultaneously.
* One ASA may support multiple independent objectives. * One ASA may support multiple independent objectives.
* The parameter described by a given objective is naturally based * The parameter(s) in the value of a given objective apply to a
on a specific service or function or action. It may in specific service or function or action. They may in principle
principle be anything that can be set to a specific logical, be anything that can be set to a specific logical, numerical or
numerical or string value, or a more complex data structure, by string value, or a more complex data structure, by a network
a network node. That node is generally expected to contain an node. Each node is expected to contain one or more ASAs which
ASA which may itself manage subsidiary non-autonomic nodes. may each manage subsidiary non-autonomic nodes.
* Discovery Objective: an objective in the process of discovery. * Discovery Objective: an objective in the process of discovery.
Its value may be undefined. Its value may be undefined.
* 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. ASAs. Thus, each ASA will maintain its own copy of the
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.
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 3.10.
o Discovery Initiator: an ASA that spontaneously starts discovery by o Discovery Initiator: an ASA that starts discovery by sending a
sending a discovery message referring to a specific discovery discovery message referring to a specific discovery objective.
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 spontaneously starts o Synchronization Initiator: an ASA that starts synchronization by
synchronization by sending a request message referring to a sending a request message referring to a specific synchronization
specific synchronization objective. objective.
o Synchronization Responder: a peer ASA which responds with the o Synchronization Responder: a peer ASA which responds with the
value of a synchronization objective. value of a synchronization objective.
o Negotiation Initiator: an ASA that spontaneously starts o Negotiation Initiator: an ASA that starts negotiation by sending a
negotiation by sending a request message referring to a specific request message referring to a specific negotiation objective.
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
protocol engine, likely including multiple threads or processes as
well as dynamic data structures such as a discovery cache, running
in a given security environment on a single device.
o Network Interface: Unless otherwise stated, this refers to a
network interface - which might be physical or virtual - that a
specific instance of GRASP is currently using. A device might
have other interfaces that are not used by GRASP.
3.2. High Level Deployment Model 3.2. High Level Deployment Model
It is expected that a GRASP implementation will reside in an A GRASP implementation will be part of the Autonomic Networking
autonomic node that also contains both the appropriate security Infrastructure in an autonomic node, which must also provide an
environment, preferably the Autonomic Control Plane (ACP) appropriate security environment. In accordance with
[I-D.ietf-anima-autonomic-control-plane], and one or more Autonomic [I-D.ietf-anima-reference-model], this SHOULD be the Autonomic
Control Plane (ACP) [I-D.ietf-anima-autonomic-control-plane]. It is
expected that GRASP will access the ACP by using a typical socket
programming interface. There will also be one or more Autonomic
Service Agents (ASAs). In the minimal case of a single-purpose Service Agents (ASAs). In the minimal case of a single-purpose
device, these three components might be fully integrated. A more device, these components might be fully integrated. A more common
common model is expected to be a multi-purpose device capable of model is expected to be a multi-purpose device capable of containing
containing several ASAs. In this case it is expected that the ACP, several ASAs. In this case it is expected that the ACP, GRASP and
GRASP and the ASAs will be implemented as separate processes, which the ASAs will be implemented as separate processes, which are
are probably multi-threaded to support asynchronous and simultaneous probably multi-threaded to support asynchronous and simultaneous
operations. It is expected that GRASP will access the ACP by using a operations.
typical socket interface. A well defined Application Programming
Interface (API) will be needed between GRASP and the ASAs. In some
implementations, ASAs would run in user space with a GRASP library
providing the API, and this library would in turn communicate via
system calls with core GRASP functions. For further details of
possible deployment models, see [I-D.ietf-anima-reference-model].
A GRASP instance must be aware of its network interfaces, and of its In some scenarios, a limited negotiation model might be deployed
own global-scope and link-local addresses. In the presence of the based on a limited trust relationship such as that between two
ACP, such information will be available from the adjacency table administrative domains. ASAs might then exchange limited information
discussed in [I-D.ietf-anima-reference-model]. In other cases, GRASP and negotiate some particular configurations.
must determine such information for itself. Details depend on the
operating system.
Because GRASP needs to work whatever happens, especially during A suitable Application Programming Interface (API) will be needed
bootstrapping and during fault conditions, it is essential that every between GRASP and the ASAs. In some implementations, ASAs would run
implementation is as robust as possible. For example, discovery in user space with a GRASP library providing the API, and this
failures, or any kind of socket error at any time, must not cause library would in turn communicate via system calls with core GRASP
irrecoverable failures in GRASP itself, and must return suitable functions. Details of the API are out of scope for the present
error codes through the API so that ASAs can also recover. document. For further details of possible deployment models, see
[I-D.ietf-anima-reference-model].
GRASP must always start up correctly after a system restart. All run An instance of GRASP must be aware of the network interfaces it will
time error conditions, and events such as address renumbering, use, and of the appropriate global-scope and link-local addresses.
network interface failures, and CPU sleep/wake cycles, must be
handled in such a way that GRASP will still operate correctly and In the presence of the ACP, such information will be available from
securely (Section 3.5.1) afterwards. the adjacency table discussed in [I-D.ietf-anima-reference-model].
In other cases, GRASP must determine such information for itself.
Details depend on the device and operating system. In the rest of
this document, the term 'interfaces' refers only to the set of
network interfaces that a specific instance of GRASP is currently
using.
Because GRASP needs to work with very high reliability, especially
during bootstrapping and during fault conditions, it is essential
that every implementation is as robust as possible. For example,
discovery failures, or any kind of socket exception at any time, must
not cause irrecoverable failures in GRASP itself, and 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
error conditions, and events such as address renumbering, network
interface failures, and CPU sleep/wake cycles, must be handled in
such a way that GRASP will still operate correctly and securely
(Section 3.5.1) 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. However, scenarios where multiple instances of by multiple ASAs. Possible exceptions are mentioned below.
GRASP run in a single node, perhaps with different security
properties, are not excluded. In this case, each instance MUST
listen independently for GRASP link-local multicasts in order for
discovery and flooding to work correctly.
3.3. High Level Design Choices 3.3. High Level Design Choices
This section describes a behavior model and design choices for GRASP, This section describes a behavior model and design choices for GRASP,
supporting discovery, synchronization and negotiation, to act as a supporting discovery, synchronization and negotiation, to act as a
platform for different technical objectives. platform for different technical objectives.
o A generic platform o A generic platform:
The protocol is designed as a generic platform, which is
independent from the synchronization or negotiation contents. It
takes care of the general intercommunication between counterparts.
The technical contents will vary according to the various
technical objectives and the different pairs of counterparts.
o The protocol is expected to form part of an Autonomic Networking
Infrastructure [I-D.ietf-anima-reference-model]. It will provide
services to ASAs via a suitable application programming interface
(API), which will reflect the protocol elements but will not
necessarily be in one-to-one correspondence to them. This API is
out of scope for the present document.
o It is normally expected that a single main instance of GRASP will The protocol design is generic and independent of the
exist in an autonomic node, and that the protocol engine and each synchronization or negotiation contents. The technical contents
ASA will run as independent asynchronous processes. However, will vary according to the various technical objectives and the
separate GRASP instances may exist for security-related reasons different pairs of counterparts.
(Section 3.5.2).
o Security infrastructure and trust relationship o Normally, a single main instance of the GRASP protocol engine will
exist in an autonomic node, and each ASA will run as an
independent asynchronous process. However, scenarios where
multiple instances of GRASP run in a single node, perhaps with
different security properties, are possible (Section 3.5.2). In
this case, each instance MUST listen independently for GRASP link-
local multicasts, and all instances MUST be woken by each such
multicast, in order for discovery and flooding to work correctly.
Because this negotiation protocol may directly cause changes to o Security infrastructure:
device configurations and bring significant impacts to a running
network, this protocol is required to run within an existing
secure environment with strong authentication. As a design
choice, the protocol itself is not provided with built-in security
functionality.
On the other hand, a limited negotiation model might be deployed As noted above, the protocol itself has no built-in security
based on a limited trust relationship such as that between two functionality, and relies on a separate secure infrastructure.
administrative domains. ASAs might then exchange limited
information and negotiate some particular configurations.
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 3.5.4. 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
according to a uniform pattern. The values that they contain according to a uniform pattern. The values that they contain
could be carried either in a simple binary format or in a complex could be carried either in a simple binary format or in a complex
object format. The basic protocol design uses the Concise Binary object format. The basic protocol design uses the Concise Binary
Object Representation (CBOR) [RFC7049], which is readily Object Representation (CBOR) [RFC7049], which is readily
extensible for unknown future requirements. extensible for unknown future requirements.
o A flexible model for synchronization o A flexible model for synchronization:
GRASP supports bilateral synchronization, which could be used to GRASP supports synchronization between two nodes, which could be
perform synchronization among a small number of nodes. It also used repeatedly to perform synchronization among a small number of
supports an unsolicited flooding mode when large groups of nodes, nodes. It also supports an unsolicited flooding mode when large
possibly including all autonomic nodes, need data for the same groups of nodes, possibly including all autonomic nodes, need data
technical objective. for the same technical objective.
* There may be some network parameters for which a more * There may be some network parameters for which a more
traditional flooding mechanism such as DNCP [RFC7787] is traditional flooding mechanism such as DNCP [RFC7787] is
considered more appropriate. GRASP can coexist with DNCP. considered more appropriate. GRASP can coexist with DNCP.
o A simple initiator/responder model for negotiation o A simple initiator/responder model for negotiation:
Multi-party negotiations are very complicated to model and cannot Multi-party negotiations are very complicated to model and cannot
readily be guaranteed to converge. GRASP uses a simple bilateral readily be guaranteed to converge. GRASP uses a simple bilateral
model and can support multi-party negotiations by indirect steps. model and can support multi-party negotiations by indirect steps.
o Organizing of synchronization or negotiation content o Organizing of synchronization or negotiation content:
The technical content transmitted by GRASP will be organized The technical content transmitted by GRASP will be organized
according to the relevant function or service. The objectives for according to the relevant function or service. The objectives for
different functions or services are kept separate, because they different functions or services are kept separate, because they
may be negotiated or synchronized with different counterparts or may be negotiated or synchronized with different counterparts or
have different response times. Thus a normal arrangement would be have different response times. Thus a normal arrangement would be
a single ASA managing a small set of closely related objectives, a single ASA managing a small set of closely related objectives,
with a version of that ASA in each relevant autonomic node. with a version of that ASA in each relevant autonomic node.
Further discussion of this aspect is out of scope for the current Further discussion of this aspect is out of scope for the current
document. document.
o Requests and responses in negotiation procedures o Requests and responses in negotiation procedures:
The initiator can negotiate a specific negotiation objective with The initiator can negotiate a specific negotiation objective with
relevant counterpart ASAs. It can request relevant information relevant counterpart ASAs. It can request relevant information
from a counterpart so that it can coordinate its local from a counterpart so that it can coordinate its local
configuration. It can request the counterpart to make a matching configuration. It can request the counterpart to make a matching
configuration. It can request simulation or forecast results by configuration. It can request simulation or forecast results by
sending some dry run conditions. sending some dry run conditions.
Beyond the traditional yes/no answer, the responder can reply with Beyond the traditional yes/no answer, the responder can reply with
a suggested alternative value for the objective concerned. This a suggested alternative value for the objective concerned. This
would start a bi-directional negotiation ending in a compromise would start a bi-directional negotiation ending in a compromise
between the two ASAs. between the two ASAs.
o Convergence of negotiation procedures o Convergence of negotiation procedures:
To enable convergence, when a responder suggests a new value or To enable convergence, when a responder suggests a new value or
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, i.e. 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. In most cases new semantics GRASP does not have a version number, and could be extended by
will be added by defining new synchronization or negotiation adding new message types and options. In normal use, new
objectives. However, the protocol could be extended by adding new semantics will be added by defining new synchronization or
message types and options in future. negotiation objectives.
3.4. Quick Operating Overview 3.4. Quick Operating Overview
GRASP is expected to run as an operating system 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
less privileged ASAs. Thus ASAs may operate without special various ASAs. These ASAs may operate without special privilege,
privilege, unless they need it for other reasons (such as configuring unless they need it for other reasons (such as configuring IP
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 serialise it for
transmission in CBOR, which is no restriction at all in practice. transmission in CBOR, which is no restriction at all in practice.
The 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
a negotiation step message (M_NEGOTIATE) for each ASA to use in a negotiation step message (M_NEGOTIATE) for each ASA to use in
turn. Two other functions support negotiating steps (M_WAIT, turn. Two other functions support negotiating steps (M_WAIT,
M_END). M_END).
o A synchronization mechanism (M_REQ_SYN), by which an ASA can o A synchronization mechanism (M_REQ_SYN), by which an ASA can
request the current value of an objective from a counterpart ASA. request the current value of an objective from a counterpart ASA.
With this, there is a corresponding response function (M_SYNCH) With this, there is a corresponding response function (M_SYNCH)
for an ASA that wishes to respond to synchronization requests. for an ASA that wishes to respond to synchronization requests.
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 AN so that any value of an objective to be flooded throughout the autonomic
ASA can receive it. One application of this is to act as an network so that any ASA can receive it. One application of this
announcement, avoiding the need for discovery of a widely is to act as an announcement, avoiding the need for discovery of a
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 3.5. GRASP Protocol Basic Properties and Mechanisms
3.5.1. Required External Security Mechanism 3.5.1. 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 if possible. A GRASP implementation MUST verify whether multicast when it is virtualized over the ACP. A GRASP instance MUST
the ACP is operational. verify whether the ACP is operational.
If there is no ACP, the protocol MUST use another form of strong If there is no ACP, one of the following alternatives applies:
authentication and SHOULD use a form of strong encryption. See
Section 3.5.2.1 for further discussion. 1. The protocol instance MUST use another form of strong
authentication and SHOULD use a form of strong encryption. 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
being part of the ACP or not. All the interfaces 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 3.5.2. Constrained Instances
This section describes some examples of cases where additional This section describes some cases where additional instances of GRASP
instances of GRASP subject to certain constraints are appropriate. subject to certain constraints are appropriate.
3.5.2.1. No ACP 3.5.2.1. No ACP
As mentioned in Section 3.3, some GRASP operations might be performed As mentioned in Section 3.3, 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 SHOULD be encrypted. structures. Messages MUST be authenticated and SHOULD be encrypted.
TLS [RFC5246] and DTLS [RFC6347] based on a Public Key Infrastructure TLS [RFC5246] and DTLS [RFC6347] based on a Public Key Infrastructure
(PKI) [RFC5280] are RECOMMENDED for this purpose. Further details (PKI) [RFC5280] are RECOMMENDED for this purpose. Further details
are out of scope for this document. are out of scope for this document.
3.5.2.2. Discovery Unsolicited Link-Local 3.5.2.2. 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 minimise 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
initialisation 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 and MUST be confined to a separate insecure instance of
GRASP with its own copy of all GRASP data structures. This instance GRASP with its own copy of all GRASP data structures. This instance
is nicknamed DULL - Discovery Unsolicited Link-Local. 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 MUST only send Discovery or Flood Synchronization
link-local multicast messages with a loop count of 1. A responder link-local multicast messages with a loop count of 1. Other GRASP
SHOULD NOT send a Discovery Response message unless it cannot be message types MUST NOT be sent.
avoided. 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.
o A Discovery Response MUST indicate a link-local address. o A Discovery Response MUST indicate a link-local address.
o A Discovery Response MUST NOT include a Divert option. o A Discovery Response MUST NOT include a Divert option.
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.
GRASP traffic SHOULD be minimized by using only Flood Synchronization To minimize traffic possibly observed by third parties, GRASP traffic
to announce objectives and their associated locators, rather than by SHOULD be minimized by using only Flood Synchronization to announce
using Discovery and Response. Further details are out of scope for objectives and their associated locators, rather than by using
this document Discovery and Response. Further details are out of scope for this
document
3.5.2.3. Secure Only Neighbor Negotiation 3.5.2.3. Secure Only Neighbor Negotiation
Some services might use insecure on-link operations as in DULL, but Some services might use insecure on-link operations as in DULL, but
also use unicast synchronization or negotiation operations protected also use unicast synchronization or negotiation operations protected
by TLS. A separate instance of GRASP is used, with its own copy of by TLS. A separate instance of GRASP is used, with its own copy of
all GRASP data structures. This instance is nicknamed SONN - Secure all GRASP data structures. This instance is nicknamed SONN - Secure
Only Neighbor Negotiation. Only Neighbor Negotiation.
The detailed rules for the SONN instance of GRASP are as follows: The detailed rules for the SONN instance of GRASP are as follows:
o Any type of GRASP message MAY be sent. o All types of GRASP message are permitted.
o An initiator MUST send any Discovery or Flood Synchronization o An initiator MUST send any Discovery or Flood Synchronization
link-local multicast messages with a loop count of 1. link-local multicast messages with a loop count of 1.
o A responder MUST silently discard any Discovery or Flood o A responder MUST silently discard any Discovery or Flood
Synchronization message whose loop count is not 1. Synchronization message whose loop count is 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 the service concerned. Objective that is not directly part of the service concerned.
o A responder MUST NOT relay any multicast messages. o A responder MUST NOT relay any multicast messages.
o A Discovery Response MUST indicate a link-local address. o A Discovery Response MUST indicate a link-local address.
o A Discovery Response MUST NOT include a Divert option. o A Discovery Response MUST NOT include a Divert option.
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.
Further details, including TLS and PKI usage, are out of scope for Further details are out of scope for this document.
this document.
3.5.3. Transport Layer Usage 3.5.3. Transport Layer Usage
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. Nothing in principle prevents them NOT exceed the link MTU size.
from working over some other method of sending packets to all on-link
neighbors, but this is out of scope for the present specification.
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. However, GRASP It MAY support use of another transport protocol. However, GRASP
itself does not provide for error detection or retransmission. Use itself does not provide for error detection or retransmission. Use
of an unreliable transport protocol is therefore NOT RECOMMENDED. of an unreliable transport protocol is therefore NOT RECOMMENDED.
Nevertheless, when running within a secure ACP on reliable Nevertheless, when running within a secure ACP on reliable
infrastructure, UDP MAY be used for unicast messages not exceeding infrastructure, UDP MAY be used for unicast messages not exceeding
the minimum IPv6 path MTU; however, TCP MUST be used for longer the minimum IPv6 path MTU; however, TCP MUST be used for longer
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3.5.4. Discovery Mechanism and Procedures 3.5.4. Discovery Mechanism and Procedures
3.5.4.1. Separated discovery and negotiation mechanisms 3.5.4.1. 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 3.8.4)
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. initiator towards another more suitable ASA. However, this response
may be delayed if the recipient needs to relay the discovery onwards,
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.
The initiator of a discovery action for a given objective need not be The initiator of a discovery action for a given objective need not be
capable of responding to that objective as a Negotiation Counterpart, capable of responding to that objective as a Negotiation Counterpart,
as a Synchronization Responder or as source for flooding. For as a Synchronization Responder or as source for flooding. For
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
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the scope of GRASP. the scope of GRASP.
3.5.4.2. Discovery Overview 3.5.4.2. 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 will respond with a cached
discovery response if any. However, it SHOULD NOT respond with a discovery response if any. However, it SHOULD NOT respond with a
cached response on an interface if it learnt that information from cached response on an interface if it learnt that information from
the same interface. If it has no cached response, it will relay the the same interface, because the peer in question will answer directly
discovery on its other interfaces, for example reaching a higher- if still operational. If it has no cached response, it will relay
the discovery on its other interfaces, for example reaching a higher-
level gateway in a hierarchical network. If a node receiving the level gateway in a hierarchical network. If a node receiving the
relayed discovery supports the discovery objective, it will respond relayed discovery supports the discovery objective, it will respond
to the relayed discovery. If it has a cached response, it will to the relayed discovery. If it has a cached response, it will
respond with that. If not, it will repeat the discovery process, respond with that. If not, it will repeat the discovery process,
which thereby becomes recursive. The loop count and timeout will which thereby becomes iterative. The loop count and timeout will
ensure that the process ends. ensure that the process ends.
Exceptionally, a Discovery message MAY be sent unicast (via UDP or A Discovery message MAY be sent unicast (via UDP or TCP) to a peer
TCP) to a peer node, which will then proceed exactly as if the node, which SHOULD then proceed exactly as if the message had been
message had been multicast, except that when TCP is used, the multicast, except that when TCP is used, the response will be on the
response will be on the same socket as the query. However, this mode same socket as the query. However, this mode does not guarantee
does not guarantee successful discovery in the general case. successful discovery in the general case.
3.5.4.3. Discovery Procedures 3.5.4.3. 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. Every Discovery message is sent by a discovery initiator objective. A Discovery message is sent by a discovery initiator via
via UDP to the ALL_GRASP_NEIGHBOR 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 3.6). 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 core and not of an individual ASA. As a result, each ASA will GRASP instance and not of an individual ASA. As a result, each ASA
need to register the objectives that it supports with the GRASP core. will need to register the objectives that it supports with the local
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 3.8.5) 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.
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If no discovery response is received within a reasonable timeout If no discovery response is received within a reasonable timeout
(default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the Discovery (default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the Discovery
message MAY be repeated, with a newly generated Session ID message MAY be repeated, with a newly generated Session ID
(Section 3.7). An exponential backoff SHOULD be used for subsequent (Section 3.7). An exponential backoff SHOULD be used for subsequent
repetitions, to limit the load during busy periods. Frequent repetitions, to limit the load during busy periods. Frequent
repetition might be symptomatic of a denial of service attack. 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 MUST cache this
information, including the interface identifier via which it was information, including the interface index 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 and
a mechanism to flush the discovery cache SHOULD be implemented. The a mechanism to flush the discovery cache MUST be implemented. 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
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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 3.5.4.4. 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 interfaces. We running in a router) MUST support discovery on all interfaces. We
refer to this as a 'relaying instance'. refer to this as a 'relaying instance'.
However, different interfaces can be at different security levels: Constrained Instances (Section 3.5.2) are always single-interface
each group of interfaces with the same security level SHOULD be instances and therefore MUST NOT perform discovery relaying.
serviced by the same GRASP process, except for Limited Security
Instances Section 3.5.2 which are always single-interface instances
and 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 Discovery message as a link-local relay the query by re-issuing a new Discovery message as a link-local
multicast on its other interfaces. multicast on its other 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 3.8.4). 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. and is never used to address Response packets, which are sent to the
relaying instance, not the original initiator.
Since the relay device is unaware of the timeout set by the original 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 initiator it SHOULD set a timeout at least equal to GRASP_DEF_TIMEOUT
milliseconds. 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. It MUST cache the Session ID
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any Discovery Responses have arrived or the discovery process has any Discovery Responses have arrived or the discovery process has
timed out. To prevent loops, it MUST NOT relay a Discovery message timed out. To prevent loops, it MUST NOT relay a Discovery message
which carries a given cached Session ID and initiator address more which carries a given cached Session ID and initiator address more
than once. These precautions avoid discovery loops and mitigate than once. These precautions avoid discovery loops and mitigate
potential overload. potential overload.
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.
This relayed discovery mechanism, with caching of the results, should
be sufficient to support most network bootstrapping scenarios.
3.5.4.5. Rapid Mode (Discovery/Negotiation binding) 3.5.4.5. Rapid Mode (Discovery/Negotiation binding)
A Discovery message MAY include a Negotiation Objective option. This A Discovery message MAY include a Negotiation Objective option. This
allows a rapid mode of negotiation described in Section 3.5.5. A allows a rapid mode of negotiation described in Section 3.5.5. A
similar mechanism is defined for synchronization in Section 3.5.6. similar mechanism is defined for synchronization in Section 3.5.6.
Note that rapid mode is currently limited to a single objective for Note that rapid mode is currently limited to a single objective for
simplicity of design and implementation. A possible future extension simplicity of design and implementation. A possible future extension
is to allow multiple objectives in rapid mode for greater efficiency. is to allow multiple objectives in rapid mode for greater efficiency.
3.5.5. Negotiation Procedures 3.5.5. Negotiation Procedures
A negotiation initiator sends a negotiation request to a counterpart A negotiation initiator sends a negotiation request (using M_REQ_NEG)
ASA, including a specific negotiation objective. It may request the to a counterpart ASA, including a specific negotiation objective. It
negotiation counterpart to make a specific configuration. may request the negotiation counterpart to make a specific
Alternatively, it may request a certain simulation or forecast result configuration. Alternatively, it may request a certain simulation or
by sending a dry run configuration. The details, including the forecast result by sending a dry run configuration. The details,
distinction between dry run and an actual configuration change, will including the distinction between dry run and an actual configuration
be defined separately for each type of negotiation objective. change, will be defined separately for each type of negotiation
objective.
If no reply message of any kind is received within a reasonable If no reply message of any kind is received within a reasonable
timeout (default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the timeout (default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the
negotiation request MAY be repeated, with a newly generated Session negotiation request MAY be repeated, with a newly generated Session
ID (Section 3.7). An exponential backoff SHOULD be used for ID (Section 3.7). An exponential backoff SHOULD be used for
subsequent repetitions. subsequent repetitions.
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
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node does not support rapid mode, discovery will continue normally. node does not support rapid mode, discovery will continue normally.
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 configured off by default and MAY be configured on function SHOULD be disabled by default.
or off by Intent.
3.5.6. Synchronization and Flooding Procedure 3.5.6. Synchronization and Flooding Procedures
3.5.6.1. Unicast Synchronization
A synchronization initiator sends a synchronization request to a A synchronization initiator sends a synchronization request to a
counterpart, including a specific synchronization objective. The counterpart, including a specific synchronization objective. The
counterpart responds with a Synchronization message (Section 3.8.10) counterpart responds with a Synchronization message (Section 3.8.10)
containing the current value of the requested synchronization containing the current value of the requested synchronization
objective. No further messages are needed. objective. No further messages are needed.
If no reply message of any kind is received within a reasonable If no reply message of any kind is received within a reasonable
timeout (default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the timeout (default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), 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 3.7). An exponential backoff SHOULD be used for
subsequent repetitions. subsequent repetitions.
3.5.6.1. Flooding 3.5.6.2. 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_NEIGHBOR multicast address (Section 3.6). ALL_GRASP_NEIGHBORS multicast address (Section 3.6).
Every network device that supports GRASP always listens to a well- Receiving flood multicasts is a function of the GRASP core, as in the
known UDP port to capture flooding messages. Because this port is case of discovery multicasts (Section 3.5.4.3).
unique in a device, this is a function of the GRASP core.
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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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. It MUST cache the
Session ID value and initiator address of each relayed Flood Session ID value and initiator address of each relayed Flood
Synchronization message for a finite time not less than twice 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 and SHOULD also act as a synchronization
responder for the objective(s) concerned. Thus nodes that require an responder for the objective(s) concerned. Thus nodes that require an
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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 3.5.1. 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 5), 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.
3.5.6.2. Rapid Mode (Discovery/Synchronization Linkage) 3.5.6.3. 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 3.8.10 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 3.5.5.1.
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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 3.6. GRASP Constants
o ALL_GRASP_NEIGHBOR 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. Additionally, MUST always listen to for link-local multicasts. This user port
this user port MAY be used to listen for TCP or UDP unicast MAY also be used to listen for TCP or UDP unicast messages in a
messages in a simple implementation of GRASP (Section 3.5.3). simple implementation of GRASP (Section 3.5.3).
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 a discovery etc. has
failed to complete. failed 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)
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3.8. GRASP Messages 3.8. GRASP Messages
3.8.1. Message Overview 3.8.1. 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. Discovery and Discovery Response (M_DISCOVERY, M_RESPONSE).
Request Negotiation, Negotiation, Confirm Waiting and Negotiation Request Negotiation, Negotiation, Confirm Waiting and Negotiation
End. End (M_REQ_NEG, M_NEGOTIATE, M_WAIT, M_END).
Request Synchronization, Synchronization, and Flood Request Synchronization, Synchronization, and Flood
Synchronization. Synchronization (M_REQ_SYN, M_SYNCH, M_FLOOD.
No Operation. No Operation and Invalid (M_NOOP, M_INVALID).
3.8.2. GRASP Message Format 3.8.2. 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 6, including
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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 3.8.13.
The various MESSAGE_TYPE values are defined in Section 6. The various MESSAGE_TYPE values are defined in Section 6.
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 6.
If an unrecognized MESSAGE_TYPE is received in a unicast message, an
Invalid message (Section 3.8.12) MAY be returned. Otherwise the
message MAY be logged and MUST be discarded. If an unrecognized
MESSAGE_TYPE is received in a multicast message, it MAY be logged and
MUST be silently discarded.
3.8.3. Message Size 3.8.3. Message Size
GRASP nodes MUST be able to receive 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 messages longer GRASP_DEF_MAX_SIZE bytes. GRASP nodes MUST NOT send unicast messages
than GRASP_DEF_MAX_SIZE bytes unless a longer size is explicitly longer than GRASP_DEF_MAX_SIZE bytes unless a longer size is
allowed for the objective concerned. For example, GRASP negotiation explicitly allowed for the objective concerned. For example, GRASP
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)
depends on the link layer technology or link adaptation layer in use.
3.8.4. Discovery Message 3.8.4. 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_NEIGHBOR 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 a low-
end implementation this MAY be GRASP_LISTEN_PORT. In a more complex end implementation this MAY be GRASP_LISTEN_PORT. In a more complex
implementation, the GRASP discovery mechanism will find, for each implementation, the GRASP discovery mechanism will find, for each
interface, a dynamic port that it can bind to for both UDP and TCP interface, a dynamic port that it can bind to for both UDP and TCP
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(Section 3.8.6). (Section 3.8.6).
o a synchronization objective option (Section 3.10.1). This is used o a synchronization objective option (Section 3.10.1). 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).
Exceptionally, a Discovery message MAY be sent unicast to a peer As mentioned in Section 3.5.4.2, a Discovery message MAY be sent
node, which will then proceed exactly as if the message had been unicast to a peer node, which SHOULD then proceed exactly as if the
multicast. message had been multicast.
3.8.5. Discovery Response Message 3.8.5. 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
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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). is treated as the default value GRASP_DEF_TIMEOUT (Section 3.6).
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 3.8.4).
In the case of a relayed Discovery message, the Discovery Response is
thus sent to the relay, not the original initiator.
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 3.9.5) 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
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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 3.9.3 and Section 3.9.4. 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 3.8.9. 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 3.8.6).
The responding node SHOULD send a Negotiation, Negotiation End or The responding node SHOULD send a Negotiation, Negotiation End or
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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 the link-local ALL_GRASP_NEIGHBOR multicast address, in accordance to port GRASP_LISTEN_PORT at the link-local ALL_GRASP_NEIGHBORS
with the rules in Section 3.5.6. multicast address, in accordance with the rules in Section 3.5.6.
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 3.8.4), 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
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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 3.8.12. 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 message that it considers invalid. The session-id MUST be incoming unicast message that it considers invalid. The session-id
copied from the incoming message. The content SHOULD be diagnostic MUST be copied from the incoming message. The content SHOULD be
information such as a partial copy of the invalid message. An diagnostic information such as a partial copy of the invalid message.
M_INVALID message MAY be silently ignored by a recipient. However, An M_INVALID message MAY be silently ignored by a recipient.
it could be used in support of extensibility, since it indicates that However, it could be used in support of extensibility, since it
the remote node does not support a new or obsolete message or option indicates that the remote node does not 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 3.8.13. 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 activate a socket. It MUST be silently ignored by a reasons needs to initialize a socket. It MUST be silently ignored by
recipient. a recipient.
3.9. GRASP Options 3.9. 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 3.9.1. 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 6. 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 are usually scoped by using encapsulation. However, GRASP options may be defined to include encapsulated GRASP options.
this is not a requirement
3.9.2. Divert Option 3.9.2. 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.
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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 error message
Note: there are scenarios where a negotiation counterpart wants to Note: there might be scenarios where an ASA wants to decline the
decline the proposed negotiation content and continue the negotiation proposed value and restart the negotiation process. In this case it
process. For these scenarios, the negotiation counterpart SHOULD use is an implementation choice whether to send a Decline option or to
a Negotiate message, with either an objective option that contains a continue with a Negotiate message, with an objective option that
data field set to indicate a meaningless initial value, or a specific contains a null value, or one that contains a new value that might
objective option that provides further conditions for convergence. achieve convergence.
3.9.5. Locator Options 3.9.5. 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
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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. Note 1: The IPv6 address MUST normally have global scope. However,
Exceptionally, during initialisation, a link-local address MAY be during initialization, a link-local address MAY be used for specific
used for specific objectives only (Section 3.5.2). In this case the objectives only (Section 3.5.2). In this case the corresponding
corresponding Discovery Response message MUST be sent via the Discovery Response message MUST be sent via the interface to which
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 3.9.5.2. 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]
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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, ?any]
objective-name = text objective-name = text
loop-count = 0..255 loop-count = 0..255
All objectives are identified by a unique name which is a case- All objectives are identified by a unique name which is a UTF-8
sensitive UTF-8 string. string, 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 7).
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:
skipping to change at page 40, line 26 skipping to change at page 40, line 49
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 3.8.7. It is also used for terminating
discovery as described in Section 3.5.4, and for terminating flooding discovery as described in Section 3.5.4, and for terminating flooding
as described in Section 3.5.6.1. as described in Section 3.5.6.2. It is placed in the objective
rather than in the GRASP message format because, as far as the ASA is
concerned, it is a property of the objective itself.
The 'any' field is to express the actual value of a negotiation or The 'any' field is to express the actual value of a negotiation or
synchronization objective. Its format is defined in the synchronization objective. Its format is defined in the
specification of the objective and may be a single value or a data specification of the objective and may be a simple value or a data
structure of any kind. It is optional because it is optional in a structure of any kind. It is optional because it is optional in a
Discovery or Discovery Response message. Discovery or Discovery Response message.
3.10.2. Objective flags 3.10.2. 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
skipping to change at page 41, line 35 skipping to change at page 42, line 11
which vary according to different functions/services. They MUST be which vary according to different functions/services. They MUST be
carried by Discovery, Request Negotiation or Negotiation messages carried by Discovery, Request Negotiation or Negotiation messages
only. The negotiation initiator MUST set the initial "loop-count" to only. The negotiation initiator MUST set the initial "loop-count" to
a value specified in the specification of the objective or, if no a value specified in the specification of the objective or, if no
such value is specified, to GRASP_DEF_LOOPCT. such value is specified, to GRASP_DEF_LOOPCT.
For most scenarios, there should be initial values in the negotiation For most scenarios, there should be initial values in the negotiation
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 bits in the value field SHOULD all be set to indicate a the value field SHOULD be set to the 'null' value defined by CBOR.
meaningless value, unless this is inappropriate for the specific
negotiation objective.
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 3.10.4. 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
skipping to change at page 42, line 26 skipping to change at page 42, line 49
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. Such modes
will be defined in the specification of such an objective. These will be defined in the specification of such an objective. These
objectives SHOULD include flags indicating the applicable mode(s). objectives SHOULD include flags indicating the applicable mode(s).
An objective may have multiple parameters. Parameters can be An issue requiring particular attention is that GRASP itself is a
categorized into two classes: the obligatory ones presented as fixed stateless protocol. Any state associated with a dry run operation,
fields; and the optional ones presented in CBOR sub-options or some such as temporarily reserving a resource for subsequent use in a live
other form of data structure embedded in CBOR. The format might be run, is entirely a matter for the designer of the ASA concerned.
inherited from an existing management or configuration protocol, the
objective option acting as a carrier for that format. The data
structure might be defined in a formal language, but that is a matter
for the specifications of individual objectives. There are many
candidates, according to the context, such as ABNF, RBNF, XML Schema,
possibly YANG, etc. The GRASP protocol itself is agnostic on these
questions.
It is NOT RECOMMENDED to split parameters in a single objective into As indicated in Section 3.1, an objective's value may include
multiple options, unless they have different response periods. An multiple parameters. Parameters might be categorized into two
exception scenario may also be described by split objectives. classes: the obligatory ones presented as fixed fields; and the
optional ones presented in some other form of data structure embedded
in CBOR. The format might be inherited from an existing management
or configuration protocol, with the objective option acting as a
carrier for that format. The data structure might be defined in a
formal language, but that is a matter for the specifications of
individual objectives. There are many candidates, according to the
context, such as ABNF, RBNF, XML Schema, YANG, etc. The GRASP
protocol itself is agnostic on these questions. The only restriction
is that the format can be mapped into CBOR.
It is NOT RECOMMENDED to mix parameters that have significantly
different response time characteristics in a single objective.
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 3.3, 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 3.1. 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
skipping to change at page 44, line 22 skipping to change at page 45, line 5
4.2. Python Implementation 4.2. 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-08. Limitations o Coverage: Corresponds to draft-ietf-anima-grasp-10. Limitations
include: include:
* insecure: uses a dummy ACP module and does not implement TLS * insecure: uses a dummy ACP module and does not implement TLS
* 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
skipping to change at page 45, line 7 skipping to change at page 45, line 35
socket peculiarities socket peculiarities
o Licensing: Simplified BSD o Licensing: Simplified BSD
o Experience: https://www.cs.auckland.ac.nz/~brian/graspy/graspy.pdf o Experience: 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 5. Security Considerations
It is obvious that a successful attack on negotiation-enabled nodes A successful attack on negotiation-enabled nodes would be extremely
would be extremely harmful, as such nodes might end up with a harmful, as such nodes might end up with a completely undesirable
completely undesirable configuration that would also adversely affect configuration that would also adversely affect their peers. GRASP
their peers. GRASP nodes and messages therefore require full nodes and messages therefore require full protection. As explained
protection. in Section 3.5.1, GRASP MUST run within a secure environment such as
the Autonomic Control Plane [I-D.ietf-anima-autonomic-control-plane],
except for the constrained instances described in Section 3.5.2.
- 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 is intended to be deployed in a single administrative Since GRASP must be deployed in an existing secure environment,
domain operating its own trust anchor and CA, there is no need for the protocol itself specifies nothing concerning the trust anchor
a trusted public third party. In a network requiring "air gap" and certification authority.
security, such a dependency would be unacceptable.
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 3.5.1),
the Session ID (Section 3.7) will act as a nonce to provide the Session ID (Section 3.7) 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 out of scope for full analysis of the secure bootstrap process is in
the present document. [I-D.ietf-anima-bootstrapping-keyinfra].
- Authorization and Roles - Authorization and Roles
The GRASP protocol is agnostic about the role of individual ASAs The GRASP protocol is agnostic about the roles and capabilities of
and about which objectives a particular ASA is authorized to individual ASAs and about which objectives a particular ASA is
support. An implementation might support precautions such as authorized to support. An implementation might support
allowing only one ASA in a given node to modify a given objective, precautions such as allowing only one ASA in a given node to
but this may not be appropriate in all cases. For example, it modify a given objective, but this may not be appropriate in all
might be operationally useful to allow an old and a new version of cases. For example, it might be operationally useful to allow an
the same ASA to run simultaneously during an overlap period. old and a new version of the same ASA to run simultaneously during
These questions are out of scope for the present specification. an overlap period. These questions are out of scope for the
present specification.
- Privacy and confidentiality - Privacy and confidentiality
Generally speaking, no personal information is expected to be Generally speaking, no personal information is expected to be
involved in the signaling protocol, so there should be no direct involved in the signaling protocol, so there should be no direct
impact on personal privacy. Nevertheless, traffic flow paths, impact on personal privacy. Nevertheless, traffic flow paths,
VPNs, etc. could be negotiated, which could be of interest for VPNs, etc. could be negotiated, which could be of interest for
traffic analysis. Also, operators generally want to conceal traffic analysis. Also, operators generally want to conceal
details of their network topology and traffic density from details of their network topology and traffic density from
outsiders. Therefore, since insider attacks cannot be excluded in outsiders. Therefore, since insider attacks cannot be excluded in
skipping to change at page 46, line 23 skipping to change at page 47, line 5
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 therefore are sent in clear and with no authentication. They are therefore
available to on-link eavesdroppers, and could be forged by on-link available to on-link eavesdroppers, and could be forged by on-link
attackers. In the case of Discovery, the Discovery Responses are attackers. In the case of Discovery, the Discovery Responses are
unicast and will therefore be protected (Section 3.5.1), and an unicast and will therefore be protected (Section 3.5.1), and an
untrusted forger will not be able to receive responses. In the untrusted forger will not be able to receive responses. In the
case of Flood Synchronization, an on-link eavesdropper will be case of Flood Synchronization, an on-link eavesdropper will be
able to receive the flooded objectives but there is no response able to receive the flooded objectives but there is no response
message to consider. Some precautions for Flood Synchronization message to consider. Some precautions for Flood Synchronization
messages are suggested in Section 3.5.6.1. messages are suggested in Section 3.5.6.2.
- 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 3.5.4. 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. Additionally, it is of great importance that firewalls responses. It is important that firewalls prevent any GRASP
prevent any GRASP messages from entering the domain from an messages from entering the domain from an unknown source.
untrusted source.
- Security during bootstrap and discovery - Security during bootstrap and discovery
A node cannot authenticate GRASP traffic from other nodes until it A node cannot trust GRASP traffic from other nodes until the
has identified the trust anchor and can validate certificates for security environment (such as the ACP) has identified the trust
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] it 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 and GRASP 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 3.5.2.
- 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 3.5.1). 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 6. CDDL Specification of GRASP
<CODE BEGINS> <CODE BEGINS>
grasp-message = (message .within message-structure) / noop-message grasp-message = (message .within message-structure) / noop-message
skipping to change at page 49, line 27 skipping to change at page 50, line 10
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
<CODE ENDS> <CODE ENDS>
7. IANA Considerations 7. 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 3.6 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_NEIGHBOR 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_NEIGHBOR 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 3.6 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
skipping to change at page 50, line 35 skipping to change at page 51, line 27
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. Future values MUST be assigned using the Specification
Required policy defined by [RFC5226]. The following initial values Required policy defined by [RFC5226].
are assigned by this document:
To assist expert review of a new objective, the specification should
include a precise description of the format of the new objective,
with sufficient explanation of its semantics to allow independent
implementations. See Section 3.10.3 for more details. If the new
objective is similar in name or purpose to a previously registered
objective, the specification should explain why a new objective is
justified.
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 8. 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 review inputs were received from
Joel Halpern, Toerless Eckert and Michael Richardson. Toerless Eckert, Joel Halpern, Barry Leiba, Charles E. Perkins, and
Michael Richardson.
Valuable comments were received from Michael Behringer, Jeferson Valuable comments were received from Michael Behringer, Jeferson
Campos Nobre, Laurent Ciavaglia, Zongpeng Du, Yu Fu, Zhenbin Li, Campos Nobre, Laurent Ciavaglia, Zongpeng Du, Yu Fu, Zhenbin Li,
Dimitri Papadimitriou, Pierre Peloso, Reshad Rahman, Markus Stenberg, Dimitri Papadimitriou, Pierre Peloso, Reshad Rahman, Markus Stenberg,
Rene Struik, Dacheng Zhang, and other participants in the NMRG Rene Struik, Dacheng Zhang, and other participants in the NMRG
research group and the ANIMA working group. research group and the ANIMA working group.
9. References 9. References
9.1. Normative References 9.1. Normative References
skipping to change at page 52, line 30 skipping to change at page 53, line 30
[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-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-04 (work in progress), October 2016. plane-05 (work in progress), January 2017.
[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-04 (work in progress), October 2016. keyinfra-04 (work in progress), October 2016.
[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-02 (work in progress), July 2016. anima-reference-model-02 (work in progress), July 2016.
[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-
anima-stable-connectivity-01 (work in progress), July anima-stable-connectivity-02 (work in progress), February
2016. 2017.
[I-D.ietf-netconf-restconf]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", draft-ietf-netconf-restconf-18 (work in
progress), October 2016.
[I-D.liang-iana-pen] [I-D.liang-iana-pen]
Liang, P., Melnikov, A., and D. Conrad, "Private Liang, P., Melnikov, A., and D. Conrad, "Private
Enterprise Number (PEN) practices and Internet Assigned Enterprise Number (PEN) practices and Internet Assigned
Numbers Authority (IANA) registration considerations", Numbers Authority (IANA) registration considerations",
draft-liang-iana-pen-06 (work in progress), July 2015. draft-liang-iana-pen-06 (work in progress), July 2015.
[I-D.liu-anima-grasp-api] [I-D.liu-anima-grasp-api]
Carpenter, B., Liu, B., Wang, W., and X. Gong, "Generic Carpenter, B., Liu, B., Wang, W., and X. Gong, "Generic
Autonomic Signaling Protocol Application Program Interface Autonomic Signaling Protocol Application Program Interface
(GRASP API)", draft-liu-anima-grasp-api-02 (work in (GRASP API)", draft-liu-anima-grasp-api-03 (work in
progress), September 2016. progress), February 2017.
[I-D.stenberg-anima-adncp] [I-D.stenberg-anima-adncp]
Stenberg, M., "Autonomic Distributed Node Consensus Stenberg, M., "Autonomic Distributed Node Consensus
Protocol", draft-stenberg-anima-adncp-00 (work in Protocol", draft-stenberg-anima-adncp-00 (work in
progress), March 2015. progress), March 2015.
[RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, DOI 10.17487/RFC2205, Functional Specification", RFC 2205, DOI 10.17487/RFC2205,
September 1997, <http://www.rfc-editor.org/info/rfc2205>. September 1997, <http://www.rfc-editor.org/info/rfc2205>.
skipping to change at page 55, line 35 skipping to change at page 56, line 30
<http://www.rfc-editor.org/info/rfc7576>. <http://www.rfc-editor.org/info/rfc7576>.
[RFC7787] Stenberg, M. and S. Barth, "Distributed Node Consensus [RFC7787] Stenberg, M. and S. Barth, "Distributed Node Consensus
Protocol", RFC 7787, DOI 10.17487/RFC7787, April 2016, Protocol", RFC 7787, DOI 10.17487/RFC7787, April 2016,
<http://www.rfc-editor.org/info/rfc7787>. <http://www.rfc-editor.org/info/rfc7787>.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking [RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016, <http://www.rfc-editor.org/info/rfc7788>. 2016, <http://www.rfc-editor.org/info/rfc7788>.
Appendix A. Open Issues [RFC Editor: Please remove if empty] [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<http://www.rfc-editor.org/info/rfc8040>.
o 63. Placeholder Appendix A. Open Issues [RFC Editor: This section should be empty.
Please remove]
o 63. Should encryption be MUST instead of SHOULD in Section 3.5.1
and Section 3.5.2.1?
o 64. Should more security text be moved from the main text into
the Security Considerations?
o 65. Do we need to formally restrict Unicode characters allowed in
objective names?
o 66. Split requirements into separate document?
o 67. Remove normative dependency on draft-greevenbosch-appsawg-
cbor-cddl?
Appendix B. Closed Issues [RFC Editor: Please remove] Appendix B. Closed Issues [RFC Editor: Please remove]
o 1. UDP vs TCP: For now, this specification suggests UDP and TCP o 1. UDP vs TCP: For now, this specification suggests UDP and TCP
as message transport mechanisms. This is not clarified yet. UDP as message transport mechanisms. This is not clarified yet. UDP
is good for short conversations, is necessary for multicast is good for short conversations, is necessary for multicast
discovery, and generally fits the discovery and divert scenarios discovery, and generally fits the discovery and divert scenarios
well. However, it will cause problems with large messages. TCP well. However, it will cause problems with large messages. TCP
is good for stable and long sessions, with a little bit of time is good for stable and long sessions, with a little bit of time
consumption during the session establishment stage. If messages consumption during the session establishment stage. If messages
skipping to change at page 59, line 43 skipping to change at page 61, line 10
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 3.5.6.1). o 27. Security of Flood multicasts (Section 3.5.6.2).
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 43 skipping to change at page 65, line 12
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.
Appendix C. Change log [RFC Editor: Please remove] Appendix C. Change log [RFC Editor: Please remove]
draft-ietf-anima-grasp-10, 2017-03-10:
Updates following IETF Last call:
Protocol change: Specify that an objective with no initial value
should have its value field set to CBOR 'null'.
Protocol change: Specify behavior on receiving unrecognized message
type.
Noted that UTF-8 names are matched byte-for-byte.
Added brief guidance for Expert Reviewer of new generic objectives.
Numerous editorial improvements and clarifications and minor text
rearrangements, none intended to change the meaning.
draft-ietf-anima-grasp-09, 2016-12-15: draft-ietf-anima-grasp-09, 2016-12-15:
Protocol change: Add F_NEG_DRY flag to specify a "dry run" objective. Protocol change: Add F_NEG_DRY flag to specify a "dry run" objective.
Protocol change: Change M_FLOOD syntax to associate a locator with Protocol change: Change M_FLOOD syntax to associate a locator with
each objective. each objective.
Concentrated mentions of TLS in one section, with all details out of Concentrated mentions of TLS in one section, with all details out of
scope. scope.
skipping to change at page 73, line 27 skipping to change at page 75, line 15
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. However, it has some flexibility, having
been extended for MPLS label distribution [RFC3209]. A more generic been extended for MPLS label distribution [RFC3209]. A more generic
design is General Internet Signalling Transport (GIST) [RFC5971], but design is General Internet Signalling Transport (GIST) [RFC5971], but
it is complex, tries to solve many problems, and is also aimed at it is complex, tries to solve many problems, and is also aimed at
per-flow signaling across many hops rather than at device-to-device per-flow signaling across many hops rather than at device-to-device
signaling. However, we cannot completely exclude extended RSVP or signaling. However, we cannot completely exclude extended RSVP or
GIST as a synchronization and negotiation protocol. They do not GIST as a synchronization and negotiation protocol. They do not
appear to be directly useable for peer discovery. appear to be directly useable for peer discovery.
We now consider two protocols that are works in progress at the time RESTCONF [RFC8040] is a protocol intended to convey NETCONF
of this writing. Firstly, RESTCONF [I-D.ietf-netconf-restconf] is a information expressed in the YANG language via HTTP, including the
protocol intended to convey NETCONF information expressed in the YANG ability to transit HTML intermediaries. While this is a powerful
language via HTTP, including the ability to transit HTML approach in the context of centralised configuration of a complex
intermediaries. While this is a powerful approach in the context of network, it is not well adapted to efficient interactive negotiation
centralised configuration of a complex network, it is not well between peer devices, especially simple ones that might not include
adapted to efficient interactive negotiation between peer devices, YANG processing already.
especially simple ones that might not include YANG processing
already.
Secondly, we consider Distributed Node Consensus Protocol (DNCP) The Distributed Node Consensus Protocol (DNCP) [RFC7787] is defined
[RFC7787]. This is defined as a generic form of state as a generic form of state synchronization protocol, with a proposed
synchronization protocol, with a proposed usage profile being the usage profile being the Home Networking Control Protocol (HNCP)
Home Networking Control Protocol (HNCP) [RFC7788] for configuring [RFC7788] for configuring Homenet routers. A specific application of
Homenet routers. A specific application of DNCP for autonomic DNCP for autonomic networking was proposed in
networking was proposed in [I-D.stenberg-anima-adncp]. [I-D.stenberg-anima-adncp].
DNCP "is designed to provide a way for each participating node to DNCP "is designed to provide a way for each participating node to
publish a set of TLV (Type-Length-Value) tuples, and to provide a publish a set of TLV (Type-Length-Value) tuples, and to provide a
shared and common view about the data published... DNCP is most shared and common view about the data published... DNCP is most
suitable for data that changes only infrequently... If constant rapid suitable for data that changes only infrequently... If constant rapid
state changes are needed, the preferable choice is to use an state changes are needed, the preferable choice is to use an
additional point-to-point channel..." additional point-to-point channel..."
Specific features of DNCP include: Specific features of DNCP include:
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