draft-ietf-anima-grasp-07.txt   draft-ietf-anima-grasp-08.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: March 17, 2017 Univ. of Auckland Expires: May 3, 2017 Univ. of Auckland
B. Liu, Ed. B. Liu, Ed.
Huawei Technologies Co., Ltd Huawei Technologies Co., Ltd
September 13, 2016 October 30, 2016
A Generic Autonomic Signaling Protocol (GRASP) A Generic Autonomic Signaling Protocol (GRASP)
draft-ietf-anima-grasp-07 draft-ietf-anima-grasp-08
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 devices 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 mutually with them. The document then defines a
general protocol for discovery, synchronization and negotiation, general protocol for discovery, synchronization and negotiation,
while the technical objectives for specific scenarios are to be while the technical objectives for specific scenarios are to be
described in separate documents. An Appendix briefly discusses described in separate documents. An Appendix briefly discusses
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 17, 2017. This Internet-Draft will expire on May 3, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
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 . . . . . . . . . . . . . . . . . . . . . . . . . 4
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 . . . . . . . . . . . . . 8 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 Design Choices . . . . . . . . . . . . . . . . 11 3.2. High Level Deployment Model . . . . . . . . . . . . . . . 12
3.3. GRASP Protocol Basic Properties and Mechanisms . . . . . 15 3.3. High Level Design Choices . . . . . . . . . . . . . . . . 13
3.3.1. Required External Security Mechanism . . . . . . . . 15 3.4. Quick Operating Overview . . . . . . . . . . . . . . . . 16
3.3.2. Limited Security Instances . . . . . . . . . . . . . 15 3.5. GRASP Protocol Basic Properties and Mechanisms . . . . . 17
3.3.3. Transport Layer Usage . . . . . . . . . . . . . . . . 17 3.5.1. Required External Security Mechanism . . . . . . . . 17
3.3.4. Discovery Mechanism and Procedures . . . . . . . . . 18 3.5.2. Limited Security Instances . . . . . . . . . . . . . 17
3.3.5. Negotiation Procedures . . . . . . . . . . . . . . . 21 3.5.3. Transport Layer Usage . . . . . . . . . . . . . . . . 19
3.3.6. Synchronization and Flooding Procedure . . . . . . . 22 3.5.4. Discovery Mechanism and Procedures . . . . . . . . . 20
3.4. High Level Deployment Model . . . . . . . . . . . . . . . 24 3.5.5. Negotiation Procedures . . . . . . . . . . . . . . . 23
3.5. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 25 3.5.6. Synchronization and Flooding Procedure . . . . . . . 25
3.6. Session Identifier (Session ID) . . . . . . . . . . . . . 26 3.6. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 27
3.7. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 26 3.7. Session Identifier (Session ID) . . . . . . . . . . . . . 27
3.7.1. Message Overview . . . . . . . . . . . . . . . . . . 26 3.8. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 28
3.7.2. GRASP Message Format . . . . . . . . . . . . . . . . 27 3.8.1. Message Overview . . . . . . . . . . . . . . . . . . 28
3.7.3. Discovery Message . . . . . . . . . . . . . . . . . . 27 3.8.2. GRASP Message Format . . . . . . . . . . . . . . . . 28
3.7.4. Discovery Response Message . . . . . . . . . . . . . 28 3.8.3. Message Size . . . . . . . . . . . . . . . . . . . . 29
3.7.5. Request Messages . . . . . . . . . . . . . . . . . . 29 3.8.4. Discovery Message . . . . . . . . . . . . . . . . . . 29
3.7.6. Negotiation Message . . . . . . . . . . . . . . . . . 30 3.8.5. Discovery Response Message . . . . . . . . . . . . . 31
3.7.7. Negotiation End Message . . . . . . . . . . . . . . . 30 3.8.6. Request Messages . . . . . . . . . . . . . . . . . . 31
3.7.8. Confirm Waiting Message . . . . . . . . . . . . . 31 3.8.7. Negotiation Message . . . . . . . . . . . . . . . . . 32
3.7.9. Synchronization Message . . . . . . . . . . . . . . . 31 3.8.8. Negotiation End Message . . . . . . . . . . . . . . . 33
3.7.10. Flood Synchronization Message . . . . . . . . . . . . 31 3.8.9. Confirm Waiting Message . . . . . . . . . . . . . 33
3.7.11. No Operation Message . . . . . . . . . . . . . . . . 32 3.8.10. Synchronization Message . . . . . . . . . . . . . . . 33
3.8. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 33 3.8.11. Flood Synchronization Message . . . . . . . . . . . . 34
3.8.1. Format of GRASP Options . . . . . . . . . . . . . . . 33 3.8.12. Invalid Message . . . . . . . . . . . . . . . . . . . 35
3.8.2. Divert Option . . . . . . . . . . . . . . . . . . . . 33 3.8.13. No Operation Message . . . . . . . . . . . . . . . . 35
3.8.3. Accept Option . . . . . . . . . . . . . . . . . . . . 33 3.9. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 35
3.8.4. Decline Option . . . . . . . . . . . . . . . . . . . 34 3.9.1. Format of GRASP Options . . . . . . . . . . . . . . . 35
3.8.5. Locator Options . . . . . . . . . . . . . . . . . . . 34 3.9.2. Divert Option . . . . . . . . . . . . . . . . . . . . 36
3.9. Objective Options . . . . . . . . . . . . . . . . . . . . 36 3.9.3. Accept Option . . . . . . . . . . . . . . . . . . . . 36
3.9.1. Format of Objective Options . . . . . . . . . . . . . 36 3.9.4. Decline Option . . . . . . . . . . . . . . . . . . . 36
3.9.2. Objective flags . . . . . . . . . . . . . . . . . . . 37 3.9.5. Locator Options . . . . . . . . . . . . . . . . . . . 37
3.9.3. General Considerations for Objective Options . . . . 37 3.10. Objective Options . . . . . . . . . . . . . . . . . . . . 39
3.9.4. Organizing of Objective Options . . . . . . . . . . . 38 3.10.1. Format of Objective Options . . . . . . . . . . . . 39
3.9.5. Experimental and Example Objective Options . . . . . 39 3.10.2. Objective flags . . . . . . . . . . . . . . . . . . 40
4. Implementation Status [RFC Editor: please remove] . . . . . . 40 3.10.3. General Considerations for Objective Options . . . . 40
4.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 40 3.10.4. Organizing of Objective Options . . . . . . . . . . 41
4.2. Python Implementation . . . . . . . . . . . . . . . . . . 40 3.10.5. Experimental and Example Objective Options . . . . . 42
5. Security Considerations . . . . . . . . . . . . . . . . . . . 41 4. Implementation Status [RFC Editor: please remove] . . . . . . 42
6. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 43 4.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 42
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 45 4.2. Python Implementation . . . . . . . . . . . . . . . . . . 43
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 47 5. Security Considerations . . . . . . . . . . . . . . . . . . . 44
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 47 6. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 46
9.1. Normative References . . . . . . . . . . . . . . . . . . 47 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48
9.2. Informative References . . . . . . . . . . . . . . . . . 48 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 50
Appendix A. Open Issues . . . . . . . . . . . . . . . . . . . . 51 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 50
Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 52 9.1. Normative References . . . . . . . . . . . . . . . . . . 50
Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 59 9.2. Informative References . . . . . . . . . . . . . . . . . 51
Appendix D. Capability Analysis of Current Protocols . . . . . . 63 Appendix A. Open Issues [RFC Editor: Please remove if empty] . . 54
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 66 Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 54
Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 62
Appendix D. Example Message Formats . . . . . . . . . . . . . . 67
D.1. Discovery Example . . . . . . . . . . . . . . . . . . . . 68
D.2. Flood Example . . . . . . . . . . . . . . . . . . . . . . 68
D.3. Synchronization Example . . . . . . . . . . . . . . . . . 68
D.4. Simple Negotiation Example . . . . . . . . . . . . . . . 69
D.5. Complete Negotiation Example . . . . . . . . . . . . . . 69
Appendix E. Capability Analysis of Current Protocols . . . . . . 70
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 73
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].
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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).
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 3.2 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 mainly based on this behavior model. The relevant capabilities of
various existing protocols are reviewed in Appendix D. various 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, but also supports diversion to off-link peers. There is no
assumption of any particular form of network topology. When a device assumption of any particular form of network topology. When a device
starts up with no pre-configuration, it has no knowledge of the starts up with no pre-configuration, it has no knowledge of the
topology. The protocol itself is capable of being used in a small topology. The protocol itself is capable of being used in a small
and/or flat network structure such as a small office or home network and/or flat network structure such as a small office or home network
as well as a professionally managed network. Therefore, the as well as a professionally managed network. Therefore, the
discovery mechanism needs to be able to allow a device to bootstrap discovery mechanism needs to be able to allow a device to bootstrap
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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 spontaneously starts
negotiation by sending a request message referring to a specific negotiation by sending a 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.
3.2. High-Level Design Choices 3.2. High Level Deployment Model
This section describes a behavior model and some considerations for It is expected that a GRASP implementation will reside in an
designing a generic signaling protocol initially supporting autonomic node that also contains both the appropriate security
discovery, synchronization and negotiation, which can act as a environment, preferably the Autonomic Control Plane (ACP)
platform for different technical objectives. [I-D.ietf-anima-autonomic-control-plane], and one or more Autonomic
Service Agents (ASAs). In the minimal case of a single-purpose
device, these three components might be fully integrated. A more
common model is expected to be a multi-purpose device capable of
containing several ASAs. In this case it is expected that the ACP,
GRASP and the ASAs will be implemented as separate processes, which
are probably multi-threaded to support asynchronous and simultaneous
operations. It is expected that GRASP will access the ACP by using a
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 running in kernel mode. 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
own global-scope and link-local addresses. In the presence of the
ACP, such information will be available from 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
operating system.
Because GRASP needs to work whatever happens, 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 error 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 always start up correctly after a system restart. 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
by multiple ASAs. However, scenarios where multiple instances of
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
This section describes a behavior model and design considerations for
GRASP, supporting discovery, synchronization and negotiation, to act
as a platform for different technical objectives.
o A generic platform o A generic platform
The protocol is designed as a generic platform, which is The protocol is designed as a generic platform, which is
independent from the synchronization or negotiation contents. It independent from the synchronization or negotiation contents. It
takes care of the general intercommunication between counterparts. takes care of the general intercommunication between counterparts.
The technical contents will vary according to the various The technical contents will vary according to the various
technical objectives and the different pairs of counterparts. technical objectives and the different pairs of counterparts.
o The protocol is expected to form part of an Autonomic Networking o The protocol is expected to form part of an Autonomic Networking
Infrastructure [I-D.ietf-anima-reference-model]. It will provide Infrastructure [I-D.ietf-anima-reference-model]. It will provide
services to ASAs via a suitable application programming interface services to ASAs via a suitable application programming interface
(API), which will reflect the protocol elements but will not (API), which will reflect the protocol elements but will not
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Infrastructure [I-D.ietf-anima-reference-model]. It will provide Infrastructure [I-D.ietf-anima-reference-model]. It will provide
services to ASAs via a suitable application programming interface services to ASAs via a suitable application programming interface
(API), which will reflect the protocol elements but will not (API), which will reflect the protocol elements but will not
necessarily be in one-to-one correspondence to them. This API is necessarily be in one-to-one correspondence to them. This API is
out of scope for the present document. out of scope for the present document.
o It is normally expected that a single main instance of GRASP will o It is normally expected that a single main instance of GRASP will
exist in an autonomic node, and that the protocol engine and each exist in an autonomic node, and that the protocol engine and each
ASA will run as independent asynchronous processes. However, ASA will run as independent asynchronous processes. However,
separate GRASP instances may exist for security reasons separate GRASP instances may exist for security reasons
(Section 3.3.2). (Section 3.5.2).
o Security infrastructure and trust relationship o Security infrastructure and trust relationship
Because this negotiation protocol may directly cause changes to Because this negotiation protocol may directly cause changes to
device configurations and bring significant impacts to a running device configurations and bring significant impacts to a running
network, this protocol is assumed to run within an existing secure network, this protocol is assumed to run within an existing secure
environment with strong authentication. As a design choice, the environment with strong authentication. As a design choice, the
protocol itself is not provided with built-in security protocol itself is not provided with built-in security
functionality. functionality.
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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. These processes can also be performed independently is useful. These processes can also be performed independently
when appropriate. when appropriate.
* GRASP discovery is always available for efficient discovery of * GRASP discovery is always available for efficient discovery of
GRASP peers and allows a rapid mode of operation described in GRASP peers and allows a rapid mode of operation described in
Section 3.3.4. For some objectives, especially those concerned Section 3.5.4. For some objectives, especially those concerned
with application layer services, another discovery mechanism with application layer services, another discovery mechanism
such as the future DNS Service Discovery [RFC7558] or Service such as the future DNS Service Discovery [RFC7558] or Service
Location Protocol [RFC2608] MAY be used. The choice is left to Location Protocol [RFC2608] MAY be used. The choice is left to
the designers of individual ASAs. the designers of individual ASAs.
o A uniform pattern for technical contents o A uniform pattern for technical contents
The synchronization and negotiation contents are defined according The synchronization and negotiation contents are defined according
to a uniform pattern. They could be carried either in simple to a uniform pattern. They could be carried either in simple
binary format or in payloads described by a flexible language. binary format or in payloads described by a flexible language.
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A limited number of rounds, for example three, or a timeout, is A limited number of rounds, for example three, or a timeout, is
needed on each ASA for each negotiation objective. It may be needed on each ASA for each negotiation objective. It may be
an implementation choice, a pre-configurable parameter, or an implementation choice, a pre-configurable parameter, or
network Intent. These choices might vary between different network Intent. These choices might vary between different
types of ASA. Therefore, the definition of each negotiation types of ASA. Therefore, the definition of each negotiation
objective MUST clearly specify this, so that the negotiation objective MUST clearly specify this, so that the negotiation
can always be terminated properly. can always be terminated properly.
* Failed negotiation * Failed negotiation
There must be a well-defined procedure for concluding that a There must be a well-defined procedure for concluding that a
negotiation cannot succeed, and if so deciding what happens negotiation cannot succeed, and if so deciding what happens
next (deadlock resolution, tie-breaking, or revert to best- next (deadlock resolution, tie-breaking, or revert to best-
effort service). Again, this MUST be specified for individual effort service). Again, this MUST be specified for individual
negotiation objectives, as an implementation choice, a pre- negotiation objectives, as an implementation choice, a pre-
configurable parameter, or network Intent. configurable parameter, or network Intent.
3.3. GRASP Protocol Basic Properties and Mechanisms o Extensibility
3.3.1. Required External Security Mechanism GRASP does not have a version number. In most cases new semantics
will be added by defining new synchronization or negotiation
objectives. However, the protocol could be extended by adding new
message types and options in future.
3.4. Quick Operating Overview
GRASP is expected to run as an operating system core module,
providing an API (such as [I-D.liu-anima-grasp-api]) to interface to
less privileged ASAs. Thus ASAs may operate without special
privilege, unless they need it for other reasons (such as configuring
IP addresses or manipulating routing tables).
The GRASP mechanisms used by the ASA are built around GRASP
objectives defined as data structures containing administrative
information such as the objective's unique name, and its current
value. The format and size of the value is not restricted by the
protocol, except that it must be possible to serialise it for
transmission in CBOR, which is no restriction at all in practice.
The GRASP provides the following mechanisms:
o A discovery mechanism (M_DISCOVERY, M_RESPONSE), by which an ASA
can discover other ASAs supporting a given objective.
o A negotiation request mechanism (M_REQ_NEG), by which an ASA can
start negotiation of an objective with a counterpart ASA. Once a
negotiation has started, the process is symmetrical, and there is
a negotiation step message (M_NEGOTIATE) for each ASA to use in
turn. Two other functions support negotiating steps (M_WAIT,
M_END).
o A synchronization mechanism (M_REQ_SYN), by which an ASA can
request the current value of an objective from a counterpart ASA.
With this, there is a corresponding response function (M_SYNCH)
for an ASA that wishes to respond to synchronization requests.
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
ASA can receive it.
3.5. GRASP Protocol Basic Properties and Mechanisms
3.5.1. Required External Security Mechanism
The protocol SHOULD run within a secure Autonomic Control Plane (ACP) The protocol SHOULD run within a secure Autonomic Control Plane (ACP)
[I-D.ietf-anima-autonomic-control-plane]. The ACP is assumed to [I-D.ietf-anima-autonomic-control-plane]. The ACP is assumed to
carry all messages securely, including link-local multicast if carry all messages securely, including link-local multicast if
possible. A GRASP implementation MUST verify whether the ACP is possible. A GRASP implementation MUST verify whether the ACP is
operational. operational.
If there is no ACP, the protocol MUST use another form of strong If there is no ACP, the protocol MUST use another form of strong
authentication and SHOULD use a form of strong encryption. TLS authentication and SHOULD use a form of strong encryption. TLS
[RFC5246] is RECOMMENDED for this purpose, based on a local Public [RFC5246] is RECOMMENDED for this purpose, based on a local Public
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The ACP, or in its absence the local PKI, sets the boundary within The ACP, or in its absence the local PKI, sets the boundary within
which nodes are trusted as GRASP peers. A GRASP implementation MUST which nodes are trusted as GRASP peers. A GRASP implementation MUST
refuse to execute GRASP synchronization and negotiation functions if refuse to execute GRASP synchronization and negotiation functions if
there is neither an operational ACP nor an operational TLS or DTLS there is neither an operational ACP nor an operational TLS or DTLS
environment. 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.
3.3.2. Limited Security Instances 3.5.2. Limited Security Instances
This section describes three cases where additional instances of This section describes three cases where additional instances of
GRASP are appropriate. GRASP are appropriate.
1) As mentioned in Section 3.2, some GRASP operations might be 1) As mentioned in Section 3.3, some GRASP operations might be
performed across an administrative domain boundary by mutual performed across an administrative domain boundary by mutual
agreement. Such operations MUST be confined to a separate instance agreement. Such operations MUST be confined to a separate instance
of GRASP with its own copy of all GRASP data structures. Messages of GRASP with its own copy of all GRASP data structures. Messages
MUST be authenticated and SHOULD be encrypted. TLS is RECOMMENDED MUST be authenticated and SHOULD be encrypted. TLS is RECOMMENDED
for this purpose. for this purpose.
2) During initialisation, before a node has joined the applicable 2) During initialisation, before a node has joined the applicable
trust infrastructure, [I-D.ietf-anima-bootstrapping-keyinfra], it is trust infrastructure, [I-D.ietf-anima-bootstrapping-keyinfra], it is
impossible to secure messages. Thus, the security bootstrap process impossible to secure messages. Thus, the security bootstrap process
needs to use insecure GRASP discovery, response and flood messages. needs to use insecure GRASP discovery, response and flood messages.
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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.
3.3.3. 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. Nothing in principle prevents them
from working over some other method of sending packets to all on-link from working over some other method of sending packets to all on-link
neighbors, but this is out of scope for the present specification. 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
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to guarantee interoperability during bootstrap and startup, using TCP to guarantee interoperability during bootstrap and startup, using TCP
for discovery responses is strongly advised. for discovery responses is strongly advised.
When running without an ACP, TLS MUST be supported and used by When running without an ACP, TLS MUST be supported and used by
default, except for link-local multicast messages. DTLS MAY be default, except for link-local multicast messages. DTLS MAY be
supported as an alternative but the details are out of scope for this supported as an alternative but the details are out of scope for this
document. Transport protocols other than TCP and UDP are also out of document. Transport protocols other than TCP and UDP are also out of
scope for this document. scope for this document.
For link-local multicast, the GRASP protocol listens to the well- For link-local multicast, the GRASP protocol listens to the well-
known GRASP Listen Port (Section 3.5). For unicast transport known GRASP Listen Port (Section 3.6). For unicast transport
sessions used for discovery responses, synchronization and sessions used for discovery responses, synchronization and
negotiation, the ASA concerned normally listens on its own negotiation, the ASA concerned normally listens on its own
dynamically assigned ports, which are communicated to its peers dynamically assigned ports, which are communicated to its peers
during discovery. However, a minimal implementation MAY use the during discovery. However, a minimal implementation MAY use the
GRASP Listen Port for this purpose. GRASP Listen Port for this purpose.
3.3.4. Discovery Mechanism and Procedures 3.5.4. Discovery Mechanism and Procedures
o Separated discovery and negotiation mechanisms 3.5.4.1. Separated discovery and negotiation mechanisms
Although discovery and negotiation or synchronization are Although discovery and negotiation or synchronization are defined
defined together in the GRASP, they are separated mechanisms. together in GRASP, they are separate mechanisms. The discovery
The discovery process could run independently from the process could run independently from the negotiation or
negotiation or synchronization process. Upon receiving a synchronization process. Upon receiving a Discovery (Section 3.8.4)
Discovery (Section 3.7.3) message, the recipient node should message, the recipient node should return a response message in which
return a response message in which it either indicates itself it either indicates itself as a discovery responder or diverts the
as a discovery responder or diverts the initiator towards initiator towards another more suitable ASA.
another more suitable ASA.
The discovery action will normally be followed by a negotiation The discovery action will normally be followed by a negotiation or
or synchronization action. The discovery results could be synchronization action. The discovery results could be utilized by
utilized by the negotiation protocol to decide which ASA the the negotiation protocol to decide which ASA the initiator will
initiator will negotiate with. negotiate with.
The initiator of a discovery action for a given objective need The initiator of a discovery action for a given objective need not be
not be capable of responding to that objective as a Negotiation capable of responding to that objective as a Negotiation Counterpart,
Counterpart, as a Synchronization Responder or as source for as a Synchronization Responder or as source for flooding. For
flooding. For example, an ASA might perform discovery even if example, an ASA might perform discovery even if it only wishes to act
it only wishes to act a Synchronization Initiator or a Synchronization Initiator or Negotiation Initiator. Such an ASA
Negotiation Initiator. Such an ASA does not itself need to does not itself need to respond to discovery messages.
respond to discovery messages.
It is also entirely possible to use GRASP discovery without any It is also entirely possible to use GRASP discovery without any
subsequent negotiation or synchronization action. In this subsequent negotiation or synchronization action. In this case, the
case, the discovered objective is simply used as a name during discovered objective is simply used as a name during the discovery
the discovery process and any subsequent operations between the process and any subsequent operations between the peers are outside
peers are outside the scope of GRASP. the scope of GRASP.
o Discovery Procedures 3.5.4.2. Discovery Overview
Discovery starts as an on-link operation. The Divert option A complete discovery process will start with a multicast on the local
can tell the discovery initiator to contact an off-link ASA for link. On-link neighbors supporting the discovery objective will
that discovery objective. Every Discovery message is sent by a respond directly. A neighbor with multiple interfaces will respond
discovery initiator via UDP to the ALL_GRASP_NEIGHBOR link- with a cached discovery response if any. If not, it will relay the
local multicast address (Section 3.5). Every network device discovery on its other interfaces, for example reaching a higher-
that supports GRASP always listens to a well-known UDP port to level gateway in a hierarchical network. If a node receiving the
capture the discovery messages. Because this port is unique in relayed discovery supports the discovery objective, it will respond
a device, this is a function of the GRASP kernel and not of an to the relayed discovery. If it has a cached response, it will
individual ASA. As a result, each ASA will need to register respond with that. If not, it will repeat the discovery process,
the objectives that it supports with the GRASP kernel. which thereby becomes recursive. The loop count and timeout will
ensure that the process ends.
If an ASA in a neighbor device supports the requested discovery Exceptionally, a Discovery message MAY be sent unicast to a peer
objective, the device SHOULD respond to the link-local node, which will then proceed exactly as if the message had been
multicast with a unicast Discovery Response message multicast. However, this mode does not guarantee successful
(Section 3.7.4) with locator option(s), unless it is discovery in the general case.
temporarily unavailable. Otherwise, if the neighbor has cached
information about an ASA that supports the requested discovery
objective (usually because it discovered the same objective
before), it SHOULD respond with a Discovery Response message
with a Divert option pointing to the appropriate Discovery
Responder.
If a device has no information about the requested discovery 3.5.4.3. Discovery Procedures
objective, and is not acting as a discovery relay (see below)
it MUST silently discard the Discovery message.
If no discovery response is received within a reasonable Discovery starts as an on-link operation. The Divert option can tell
timeout (default GRASP_DEF_TIMEOUT milliseconds, Section 3.5), the discovery initiator to contact an off-link ASA for that discovery
the Discovery message MAY be repeated, with a newly generated objective. Every Discovery message is sent by a discovery initiator
Session ID (Section 3.6). An exponential backoff SHOULD be via UDP to the ALL_GRASP_NEIGHBOR link-local multicast address
used for subsequent repetitions, in order to mitigate possible (Section 3.6). Every network device that supports GRASP always
denial of service attacks. 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
GRASP kernel and not of an individual ASA. As a result, each ASA
will need to register the objectives that it supports with the GRASP
kernel.
After a GRASP device successfully discovers a locator for a If an ASA in a neighbor device supports the requested discovery
Discovery Responder supporting a specific objective, it MUST objective, the device SHOULD respond to the link-local multicast with
cache this information, including the interface identifier via a unicast Discovery Response message (Section 3.8.5) with locator
which it was discovered. This cache record MAY be used for option(s), unless it is temporarily unavailable. Otherwise, if the
future negotiation or synchronization, and the locator SHOULD neighbor has cached information about an ASA that supports the
be passed on when appropriate as a Divert option to another requested discovery objective (usually because it discovered the same
Discovery Initiator. objective before), it SHOULD respond with a Discovery Response
message with a Divert option pointing to the appropriate Discovery
Responder.
The cache mechanism MUST include a lifetime for each entry. If a device has no information about the requested discovery
The lifetime is derived from a time-to-live (ttl) parameter in objective, and is not acting as a discovery relay (see below) it MUST
each Discovery Response message. Cached entries MUST be silently discard the Discovery message.
ignored or deleted after their lifetime expires. In some
environments, unplanned address renumbering might occur. In
such cases, the lifetime SHOULD be short compared to the
typical address lifetime and a mechanism to flush the discovery
cache SHOULD be implemented. The discovery mechanism needs to
track the node's current address to ensure that Discovery
Responses always indicate the correct address.
If multiple Discovery Responders are found for the same If no discovery response is received within a reasonable timeout
objective, they SHOULD all be cached, unless this creates a (default GRASP_DEF_TIMEOUT milliseconds, Section 3.6), the Discovery
resource shortage. The method of choosing between multiple message MAY be repeated, with a newly generated Session ID
responders is an implementation choice. This choice MUST be (Section 3.7). An exponential backoff SHOULD be used for subsequent
available to each ASA but the GRASP implementation SHOULD repetitions, to limit the load during busy periods. Frequent
provide a default choice. repetition might be symptomatic of a denial of service attack.
Because Discovery Responders will be cached in a finite cache, After a GRASP device successfully discovers a locator for a Discovery
they might be deleted at any time. In this case, discovery Responder supporting a specific objective, it MUST cache this
will need to be repeated. If an ASA exits for any reason, its information, including the interface identifier via which it was
locator might still be cached for some time, and attempts to discovered. This cache record MAY be used for future negotiation or
connect to it will fail. ASAs need to be robust in these synchronization, and the locator SHOULD be passed on when appropriate
circumstances. as a Divert option to another Discovery Initiator.
A GRASP device with multiple link-layer interfaces (typically a The cache mechanism MUST include a lifetime for each entry. The
router) MUST support discovery on all interfaces. If it lifetime is derived from a time-to-live (ttl) parameter in each
receives a Discovery message on a given interface for a Discovery Response message. Cached entries MUST be ignored or
specific objective that it does not support and for which it deleted after their lifetime expires. In some environments,
has not previously cached a Discovery Responder, it MUST relay unplanned address renumbering might occur. In such cases, the
the query by re-issuing a Discovery message as a link-local lifetime SHOULD be short compared to the typical address lifetime and
multicast on its other interfaces. The relayed discovery a mechanism to flush the discovery cache SHOULD be implemented. The
message MUST have the same Session ID as the incoming discovery discovery mechanism needs to track the node's current address to
message and MUST be tagged with the IP address of its original ensure that Discovery Responses always indicate the correct address.
initiator. Since the relay device is unaware of the timeout
set by the original initiator it SHOULD set a timeout at least
equal to GRASP_DEF_TIMEOUT milliseconds.
The relaying device MUST decrement the loop count within the If multiple Discovery Responders are found for the same objective,
objective, and MUST NOT relay the Discovery message if the they SHOULD all be cached, unless this creates a resource shortage.
result is zero. Also, it MUST limit the total rate at which it The method of choosing between multiple responders is an
relays discovery messages to a reasonable value, in order to implementation choice. This choice MUST be available to each ASA but
mitigate possible denial of service attacks. It MUST cache the the GRASP implementation SHOULD provide a default choice.
Session ID value and initiator address of each relayed
Discovery message until any Discovery Responses have arrived or
the discovery process has timed out. To prevent loops, it MUST
NOT relay a Discovery message which carries a given cached
Session ID and initiator address more than once. These
precautions avoid discovery loops and mitigate potential
overload.
The discovery results received by the relaying device MUST in Because Discovery Responders will be cached in a finite cache, they
turn be sent as a Discovery Response message to the Discovery might be deleted at any time. In this case, discovery will need to
message that caused the relay action. 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.
ASAs need to be robust in these circumstances.
This relayed discovery mechanism, with caching of the results, 3.5.4.4. Discovery Relaying
should be sufficient to support most network bootstrapping
scenarios.
o A complete discovery process will start with a multicast on the A GRASP instance with multiple link-layer interfaces (typically
local link. On-link neighbors supporting the discovery objective running in a router) MUST support discovery on all interfaces. We
will respond directly. A neighbor with multiple interfaces will refer to this as a 'relaying instance'.
respond with a cached discovery response if any. If not, 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 relayed discovery supports the discovery objective,
it will respond to the relayed discovery. If it has a cached
response, it will respond with that. If not, it will repeat the
discovery process, which thereby becomes recursive. The loop
count and timeout will ensure that the process ends.
o Rapid Mode (Discovery/Negotiation binding) However, different interfaces can be at different security levels:
each group of interfaces with the same security level SHOULD be
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.
A Discovery message MAY include a Negotiation Objective option. If a relaying instance receives a Discovery message on a given
This allows a rapid mode of negotiation described in interface for a specific objective that it does not support and for
Section 3.3.5. A similar mechanism is defined for which it has not previously cached a Discovery Responder, it MUST
synchronization in Section 3.3.6. relay the query by re-issuing a Discovery message as a link-local
multicast on its other interfaces.
Note that rapid mode is currently limited to a single objective The relayed discovery message MUST have the same Session ID as the
for simplicity of design and implementation. A possible future incoming discovery message and MUST be tagged with the IP address of
extension is to allow multiple objectives in rapid mode for its original initiator (see Section 3.8.4). Since the relay device
greater efficiency. is unaware of the timeout set by the original initiator it SHOULD set
a timeout at least equal to GRASP_DEF_TIMEOUT milliseconds.
3.3.5. Negotiation Procedures The relaying instance MUST decrement the loop count within the
objective, and MUST NOT relay the Discovery message if the result is
zero. Also, it MUST limit the total rate at which it relays
discovery messages to a reasonable value, in order to mitigate
possible denial of service attacks. It MUST cache the Session ID
value and initiator address of each relayed Discovery message until
any Discovery Responses have arrived or the discovery process has
timed out. To prevent loops, it MUST NOT relay a Discovery message
which carries a given cached Session ID and initiator address more
than once. These precautions avoid discovery loops and mitigate
potential overload.
The discovery results received by the relaying instance MUST in turn
be sent as a Discovery Response message to the Discovery message that
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)
A Discovery message MAY include a Negotiation Objective option. This
allows a rapid mode of negotiation described in Section 3.5.5. A
similar mechanism is defined for synchronization in Section 3.5.6.
Note that rapid mode is currently limited to a single objective for
simplicity of design and implementation. A possible future extension
is to allow multiple objectives in rapid mode for greater efficiency.
3.5.5. Negotiation Procedures
A negotiation initiator sends a negotiation request to a counterpart A negotiation initiator sends a negotiation request to a counterpart
ASA, including a specific negotiation objective. It may request the ASA, including a specific negotiation objective. It may request the
negotiation counterpart to make a specific configuration. negotiation counterpart to make a specific configuration.
Alternatively, it may request a certain simulation or forecast result Alternatively, it may request a certain simulation or forecast result
by sending a dry run configuration. The details, including the by sending a dry run configuration. The details, including the
distinction between dry run and an actual configuration change, will distinction between dry run and an actual configuration change, will
be defined separately for each type of negotiation objective. 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 3.5), 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 3.6). 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 (accept) answer. This will end it will give an immediate positive (accept) answer. This will end
the negotiation phase immediately. Otherwise, it will negotiate. It the negotiation phase immediately. Otherwise, it will negotiate. It
will reply with a proposed alternative configuration that it can will reply with a proposed alternative configuration that it can
apply (typically, a configuration that uses fewer resources than apply (typically, a configuration that uses fewer resources than
requested by the negotiation initiator). This will start a bi- requested by the negotiation initiator). This will start a bi-
directional negotiation to reach a compromise between the two ASAs. directional negotiation to reach a compromise between the two ASAs.
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negotiations with various other ASAs, or in simultaneous negotiations negotiations with various other ASAs, or in simultaneous negotiations
about different objectives. Thus, GRASP is expected to be used in a about different objectives. Thus, GRASP is expected to be used in a
multi-threaded mode. Certain negotiation objectives may have multi-threaded mode. Certain negotiation objectives may have
restrictions on multi-threading, for example to avoid over-allocating restrictions on multi-threading, for example to avoid over-allocating
resources. resources.
Some configuration actions, for example wavelength switching in Some configuration actions, for example wavelength switching in
optical networks, might take considerable time to execute. The ASA optical networks, might take considerable time to execute. The ASA
concerned needs to allow for this by design, but GRASP does allow for concerned needs to allow for this by design, but GRASP does allow for
a peer to insert latency in a negotiation process if necessary a peer to insert latency in a negotiation process if necessary
(Section 3.7.8). (Section 3.8.9).
3.3.5.1. Rapid Mode (Discovery/Negotiation Linkage) 3.5.5.1. Rapid Mode (Discovery/Negotiation Linkage)
A Discovery message MAY include a Negotiation Objective option. In A Discovery message MAY include a Negotiation Objective option. In
this case the Discovery message also acts as a Request Negotiation this case the Discovery message also acts as a Request Negotiation
message to indicate to the Discovery Responder that it could directly message to indicate to the Discovery Responder that it could directly
reply to the Discovery Initiator with a Negotiation message for rapid reply to the Discovery Initiator with a Negotiation message for rapid
processing, if it could act as the corresponding negotiation processing, if it could act as the corresponding negotiation
counterpart. However, the indication is only advisory not counterpart. However, the indication is only advisory not
prescriptive. prescriptive.
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 configured off by default and MAY be configured on
or off by Intent. or off by Intent.
3.3.6. Synchronization and Flooding Procedure 3.5.6. Synchronization and Flooding Procedure
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 3.7.9) 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 3.5), 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 3.6). An exponential backoff SHOULD be used for Session ID (Section 3.7). An exponential backoff SHOULD be used for
subsequent repetitions. subsequent repetitions.
3.3.6.1. Flooding 3.5.6.1. 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 3.5). ALL_GRASP_NEIGHBOR multicast address (Section 3.6).
Every network device that supports GRASP always listens to a well- Every network device that supports GRASP always listens to a well-
known UDP port to capture flooding messages. Because this port is known UDP port to capture flooding messages. Because this port is
unique in a device, this is a function of the GRASP kernel. unique in a device, this is a function of the GRASP kernel.
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
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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
objective subject to flooding can either wait for the next flood or objective subject to flooding can either wait for the next flood or
request unicast synchronization for that objective. request unicast synchronization for that objective.
The multicast messages for synchronization flooding are subject to The multicast messages for synchronization flooding are subject to
the security rules in Section 3.3.1. 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.
3.3.6.2. Rapid Mode (Discovery/Synchronization Linkage) 3.5.6.2. 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 3.7.9 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. However, the indication is only advisory synchronization objective. However, the indication is only advisory
not prescriptive. not prescriptive.
It is possible that a Discovery Response will arrive from a responder It is possible that a Discovery Response will arrive from a responder
that does not support rapid mode, before such a Synchronization that does not support rapid mode, before such a Synchronization
message arrives. In this case, rapid mode will not occur. message arrives. In this case, rapid mode will not occur.
This rapid mode could reduce the interactions between nodes so that a This rapid mode could reduce the interactions between nodes so that a
higher efficiency could be achieved. However, a network in which higher efficiency could be achieved. However, a network in which
some nodes support rapid mode and others do not will have complex some nodes support rapid mode and others do not will have complex
timing-dependent behaviors. Therefore, the rapid synchronization timing-dependent behaviors. Therefore, the rapid synchronization
function SHOULD be configured off by default and MAY be configured on function SHOULD be configured off by default and MAY be configured on
or off by Intent. or off by Intent.
3.4. High Level Deployment Model 3.6. GRASP Constants
It is expected that a GRASP implementation will reside in an
autonomic node that also contains both the appropriate security
environment (preferably the ACP) and one or more Autonomic Service
Agents (ASAs). In the minimal case of a single-purpose device, these
three components might be fully integrated. A more common model is
expected to be a multi-purpose device capable of containing several
ASAs. In this case it is expected that the ACP, GRASP and the ASAs
will be implemented as separate processes, which are probably multi-
threaded to support asynchronous and simultaneous operations. It is
expected that GRASP will access the ACP by using a 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 running in kernel mode. For further details of
possible deployment models, see [I-D.ietf-anima-reference-model].
Because GRASP needs to work whatever happens, 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 error 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 always start up correctly after a system restart. 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 3.3.1) afterwards.
An autonomic node will normally run a single instance of GRASP, used
by multiple ASAs. However, scenarios where multiple instances of
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 muticasts in order for
discovery and flooding to work correctly.
3.5. GRASP Constants
o ALL_GRASP_NEIGHBOR o ALL_GRASP_NEIGHBOR
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. Additionally,
this user port MAY be used to listen for TCP or UDP unicast this user port MAY be used to listen for TCP or UDP unicast
messages in a simple implementation of GRASP (Section 3.3.3). messages in a 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.
3.6. Session Identifier (Session ID) o GRASP_DEF_MAX_SIZE (2048)
This is an up to 24-bit opaque value used to distinguish multiple The default maximum message size in bytes.
3.7. Session Identifier (Session ID)
This is an up to 32-bit opaque value used to distinguish multiple
sessions between the same two devices. A new Session ID MUST be sessions between the same two devices. A new Session ID MUST be
generated by the initiator for every new Discovery, Flood generated by the initiator for every new Discovery, Flood
Synchronization or Request message. All responses and follow-up Synchronization or Request message. All responses and follow-up
messages in the same discovery, synchronization or negotiation messages in the same discovery, synchronization or negotiation
procedure MUST carry the same Session ID. procedure MUST carry the same Session ID.
The Session ID SHOULD have a very low collision rate locally. It The Session ID SHOULD have a very low collision rate locally. It
MUST be generated by a pseudo-random algorithm using a locally MUST be generated by a pseudo-random algorithm using a locally
generated seed which is unlikely to be used by any other device in generated seed which is unlikely to be used by any other device in
the same network [RFC4086]. the same network [RFC4086]. When allocating a new Session ID, GRASP
MUST check that the value is not already in use and SHOULD check that
it has not been used recently, by consulting a cache of current and
recent sessions. In the unlikely event of a clash, GRASP MUST
generate a new value.
However, there is a finite probability that two nodes might generate However, there is a finite probability that two nodes might generate
the same Session ID value. For that reason, when a Session ID is the same Session ID value. For that reason, when a Session ID is
communicated via GRASP, the receiving node MUST tag it with the communicated via GRASP, the receiving node MUST tag it with the
initiator's IP address to allow disambiguation. Multicast GRASP initiator's IP address to allow disambiguation. In the highly
messages and their responses, which may be relayed between links, unlikely event of two peers opening sessions with the same Session ID
therefore include a field that carries the initiator's global IP value, this tag will allow the two sessions to be distinguished.
address. Multicast GRASP messages and their responses, which may be relayed
between links, therefore include a field that carries the initiator's
global IP address.
3.7. GRASP Messages There is a highly unlikely race condition in which two peers start
simultaneous negotiation sessions with each other using the same
Session ID value. Depending on various implementation choices, this
might lead to the two sessions being confused. See Section 3.8.6 for
details of how to avoid this.
3.7.1. Message Overview 3.8. GRASP Messages
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.
Request Negotiation, Negotiation, Confirm Waiting and Negotiation Request Negotiation, Negotiation, Confirm Waiting and Negotiation
End. End.
Request Synchronization, Synchronization, and Flood Request Synchronization, Synchronization, and Flood
Synchronization. Synchronization.
No Operation. No Operation.
3.7.2. 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
constants such as message types. constants such as message types.
Every GRASP message, except the No Operation message, carries a Every GRASP message, except the No Operation message, carries a
Session ID (Section 3.6). Options are then presented serially in the Session ID (Section 3.7). Options are then presented serially in the
options field. options field.
In fragmentary CDDL, every GRASP message follows the pattern: In fragmentary CDDL, every GRASP message follows the pattern:
grasp-message = (message .within message-structure) / noop-message grasp-message = (message .within message-structure) / noop-message
message-structure = [MESSAGE_TYPE, session-id, ?initiator, message-structure = [MESSAGE_TYPE, session-id, ?initiator,
*grasp-option] *grasp-option]
MESSAGE_TYPE = 1..255 MESSAGE_TYPE = 1..255
session-id = 0..16777215 ;up to 24 bits session-id = 0..4294967295 ;up to 32 bits
grasp-option = any grasp-option = any
The MESSAGE_TYPE indicates the type of the message and thus defines The MESSAGE_TYPE indicates the type of the message and thus defines
the expected options. Any options received that are not consistent the expected options. Any options received that are not consistent
with the MESSAGE_TYPE SHOULD be silently discarded. with the MESSAGE_TYPE SHOULD be silently discarded.
The No Operation (noop) message is described in Section 3.7.11. 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.
3.7.3. Discovery Message 3.8.3. Message Size
GRASP nodes MUST be able to receive messages of at least
GRASP_DEF_MAX_SIZE bytes. GRASP nodes MUST NOT send messages longer
than GRASP_DEF_MAX_SIZE bytes unless a longer size is explicitly
allowed for the objective concerned. For example, GRASP negotiation
itself could be used to agree on a longer message size.
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 the 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_NEIGHBOR multicast
address. It then listens for unicast TCP responses on the same port, address on each link-layer interface in use by GRASP. It then
and stores the discovery results (including responding discovery listens for unicast TCP responses on a given port, and stores the
objectives and corresponding unicast locators). discovery results (including responding discovery objectives and
corresponding unicast locators).
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-
end implementation this MAY be GRASP_LISTEN_PORT. In a more complex
implementation, the GRASP discovery mechanism will find, for each
interface, a dynamic port that it can bind to for both UDP and TCP
before initiating any discovery.
The 'initiator' field in the message is a globally unique IP address The 'initiator' field in the message is a globally unique IP address
of the initiator, for the sole purpose of disambiguating the Session of the initiator, for the sole purpose of disambiguating the Session
ID in other nodes. If for some reason the initiator does not have a ID in other nodes. If for some reason the initiator does not have a
globally unique IP address, it MUST use a link-local address for this globally unique IP address, it MUST use a link-local address for this
purpose that is highly likely to be unique, for example using purpose that is highly likely to be unique, for example using
[RFC7217]. [RFC7217].
A Discovery message MUST include exactly one of the following: A Discovery message MUST include exactly one of the following:
o a discovery objective option (Section 3.9.1). Its loop count MUST o a discovery objective option (Section 3.10.1). Its loop count
be set to a suitable value to prevent discovery loops (default MUST be set to a suitable value to prevent discovery loops
value is GRASP_DEF_LOOPCT). If the discovery initiator requires (default value is GRASP_DEF_LOOPCT). If the discovery initiator
only on-link responses, the loop count MUST be set to 1. requires only on-link responses, the loop count MUST be set to 1.
o a negotiation objective option (Section 3.9.1). This is used both o a negotiation objective option (Section 3.10.1). This is used
for the purpose of discovery and to indicate to the discovery both for the purpose of discovery and to indicate to the discovery
target that it MAY directly reply to the discovery initiatior with target that it MAY directly reply to the discovery initiatior with
a Negotiation message for rapid processing, if it could act as the a Negotiation message for rapid processing, if it could act as the
corresponding negotiation counterpart. The sender of such a corresponding negotiation counterpart. The sender of such a
Discovery message MUST initialize a negotiation timer and loop Discovery message MUST initialize a negotiation timer and loop
count in the same way as a Request Negotiation message count in the same way as a Request Negotiation message
(Section 3.7.5). (Section 3.8.6).
o a synchronization objective option (Section 3.9.1). 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).
3.7.4. Discovery Response Message Exceptionally, a Discovery message MAY be sent unicast to a peer
node, which will then proceed exactly as if the message had been
multicast.
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
A node which receives a Discovery message SHOULD send a Discovery A node which receives a Discovery message SHOULD send a Discovery
Response message if and only if it can respond to the discovery. Response message if and only if it can respond to the discovery.
It MUST contain the same Session ID and initiator as the Discovery It MUST contain the same Session ID and initiator as the Discovery
message. message.
It MUST contain a time-to-live (ttl) for the validity of the It MUST contain a time-to-live (ttl) for the validity of the
response, given as a positive integer value in milliseconds. Zero response, given as a positive integer value in milliseconds. Zero
is treated as the default value GRASP_DEF_TIMEOUT (Section 3.5). 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. used to send the Discovery message (as explained in Section 3.8.4).
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 3.8.5) 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
(Section 3.8.2) embedding a locator option or a combination of (Section 3.9.2) embedding a locator option or a combination of
multiple kinds of locator options which indicate the locator(s) of multiple kinds of locator options which indicate the locator(s) of
the discovery objective. the discovery objective.
More details on the processing of Discovery Responses are given in More details on the processing of Discovery Responses are given in
Section 3.3.4. Section 3.5.4.
3.7.5. Request Messages 3.8.6. Request Messages
In fragmentary CDDL, Request Negotiation and Request Synchronization In fragmentary CDDL, Request Negotiation and Request Synchronization
messages follow the patterns: messages follow the patterns:
request-negotiation-message = [M_REQ_NEG, session-id, objective] request-negotiation-message = [M_REQ_NEG, session-id, objective]
request-synchronization-message = [M_REQ_SYN, session-id, objective] request-synchronization-message = [M_REQ_SYN, session-id, objective]
A negotiation or synchronization requesting node sends the A negotiation or synchronization requesting node sends the
appropriate Request message to the unicast address (directly stored appropriate Request message to the unicast address (directly stored
or resolved from an FQDN or URI) of the negotiation or or resolved from an FQDN or URI) of the negotiation or
synchronization counterpart, using the appropriate protocol and port synchronization counterpart, using the appropriate protocol and port
numbers (selected from the discovery results). numbers (selected from the discovery results).
A Request message MUST include the relevant objective option. In the A Request message MUST include the relevant objective option. In the
case of Request Negotiation, the objective option MUST include the case of Request Negotiation, the objective option MUST include the
requested value. requested value.
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appropriate Request message to the unicast address (directly stored appropriate Request message to the unicast address (directly stored
or resolved from an FQDN or URI) of the negotiation or or resolved from an FQDN or URI) of the negotiation or
synchronization counterpart, using the appropriate protocol and port synchronization counterpart, using the appropriate protocol and port
numbers (selected from the discovery results). numbers (selected from the discovery results).
A Request message MUST include the relevant objective option. In the A Request message MUST include the relevant objective option. In the
case of Request Negotiation, the objective option MUST include the case of Request Negotiation, the objective option MUST include the
requested value. requested value.
When an initiator sends a Request Negotiation message, it MUST When an initiator sends a Request Negotiation message, it MUST
initialize a negotiation timer for the new negotiation thread with initialize a negotiation timer for the new negotiation thread. The
the value GRASP_DEF_TIMEOUT milliseconds. Unless this timeout is default is GRASP_DEF_TIMEOUT milliseconds. Unless this timeout is
modified by a Confirm Waiting message (Section 3.7.8), the initiator modified by a Confirm Waiting message (Section 3.8.9), the initiator
will consider that the negotiation has failed when the timer expires. will consider that the negotiation has failed when the timer expires.
Similarly, when an initiator sends a Request Synchronization, it
SHOULD initialize a synchronization timer. The default is
GRASP_DEF_TIMEOUT milliseconds. The initiator will consider that
synchronization has failed if there is no response before the timer
expires.
When an initiator sends a Request message, it MUST initialize the When an initiator sends a Request message, it MUST initialize the
loop count of the objective option with a value defined in the loop count of the objective option with a value defined in the
specification of the option or, if no such value is specified, with specification of the option or, if no such value is specified, with
GRASP_DEF_LOOPCT. GRASP_DEF_LOOPCT.
If a node receives a Request message for an objective for which no If a node receives a Request message for an objective for which no
ASA is currently listening, it MUST immediately close the relevant ASA is currently listening, it MUST immediately close the relevant
socket to indicate this to the initiator. socket to indicate this to the initiator.
3.7.6. Negotiation Message To avoid the highly unlikely race condition in which two nodes
simultaneously request sessions with each other using the same
Session ID (Section 3.7), when a node receives a Request message, it
MUST verify that the received Session ID is not already locally
active. In case of a clash, it MUST discard the Request message, in
which case the initiator will detect a timeout.
3.8.7. Negotiation Message
In fragmentary CDDL, a Negotiation message follows the pattern: In fragmentary CDDL, a Negotiation message follows the pattern:
discovery-message = [M_NEGOTIATE, session-id, objective] negotiate-message = [M_NEGOTIATE, session-id, objective]
A negotiation counterpart sends a Negotiation message in response to A negotiation counterpart sends a Negotiation message in response to
a Request Negotiation message, a Negotiation message, or a Discovery a Request Negotiation message, a Negotiation message, or a Discovery
message in Rapid Mode. A negotiation process MAY include multiple message in Rapid Mode. A negotiation process MAY include multiple
steps. steps.
The Negotiation message MUST include the relevant Negotiation The Negotiation message MUST include the relevant Negotiation
Objective option, with its value updated according to progress in the Objective option, with its value updated according to progress in the
negotiation. The sender MUST decrement the loop count by 1. If the negotiation. The sender MUST decrement the loop count by 1. If the
loop count becomes zero the message MUST NOT be sent. In this case loop count becomes zero the message MUST NOT be sent. In this case
the negotiation session has failed and will time out. the negotiation session has failed and will time out.
3.7.7. Negotiation End Message 3.8.8. Negotiation End Message
In fragmentary CDDL, a Negotiation End message follows the pattern: In fragmentary CDDL, a Negotiation End message follows the pattern:
end-message = [M_END, session-id, accept-option / decline-option] end-message = [M_END, session-id, accept-option / decline-option]
A negotiation counterpart sends an Negotiation End message to close A negotiation counterpart sends an Negotiation End message to close
the negotiation. It MUST contain either an accept or a decline the negotiation. It MUST contain either an accept or a decline
option, defined in Section 3.8.3 and Section 3.8.4. 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.
3.7.8. 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 3.7.5). (Section 3.8.6).
The responding node SHOULD send a Negotiation, Negotiation End or The responding node SHOULD send a Negotiation, Negotiation End or
another Confirm Waiting message before the negotiation timer expires. another Confirm Waiting message before the negotiation timer expires.
If not, the initiator MUST abandon or restart the negotiation If not, the initiator MUST abandon or restart the negotiation
procedure, to avoid an indefinite wait. procedure, to avoid an indefinite wait.
3.7.9. Synchronization Message 3.8.10. Synchronization Message
In fragmentary CDDL, a Synchronization message follows the pattern: In fragmentary CDDL, a Synchronization message follows the pattern:
synch-message = [M_SYNCH, session-id, objective] synch-message = [M_SYNCH, session-id, objective]
A node which receives a Request Synchronization, or a Discovery A node which receives a Request Synchronization, or a Discovery
message in Rapid Mode, sends back a unicast Synchronization message message in Rapid Mode, sends back a unicast Synchronization message
with the synchronization data, in the form of a GRASP Option for the with the synchronization data, in the form of a GRASP Option for the
specific synchronization objective present in the Request specific synchronization objective present in the Request
Synchronization. Synchronization.
3.7.10. Flood Synchronization Message 3.8.11. Flood Synchronization Message
In fragmentary CDDL, a Flood Synchronization message follows the In fragmentary CDDL, a Flood Synchronization message follows the
pattern: pattern:
flood-message = [M_FLOOD, session-id, initiator, ttl, flood-message = [M_FLOOD, session-id, initiator, ttl,
(locator-option / []), +objective] (locator-option / []), +objective]
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 the link-local ALL_GRASP_NEIGHBOR multicast address, in accordance
with the rules in Section 3.3.6. 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. messages.
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 response, given as a positive integer value in milliseconds. the response, 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 message MAY contain a locator option indicating the ASA that The message MAY contain a locator option indicating the ASA that
initiated the flooded data. In its absence, an empty option MUST initiated the flooded data. In its absence, an empty option MUST
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Note: the purpose of this mechanism is to allow the recipient of Note: the purpose of this mechanism is to allow the recipient of
flooded values to distinguish between different senders of the same flooded values to distinguish between different senders of the same
objective, and if necessary communicate with them using the locator, objective, and if necessary communicate with them using the locator,
protocol and port included in the locator option. Many objectives protocol and port included in the locator option. Many objectives
will not need this mechanism, so they will be flooded with a null will not need this mechanism, so they will be flooded with a null
locator. locator.
Cached entries MUST be ignored or deleted after their lifetime Cached entries MUST be ignored or deleted after their lifetime
expires. expires.
3.7.11. No Operation Message 3.8.12. Invalid Message
In fragmentary CDDL, an Invalid message follows the pattern:
invalid-message = [M_INVALID, session-id, ?any]
This message MAY be sent by an implementation in response to an
incoming message that it considers invalid. The session-id MUST be
copied from the incoming message. The content SHOULD be diagnostic
information such as a partial copy of the invalid message. An
M_INVALID message MAY be silently ignored by a recipient. However,
it could be used in support of extensibility, since it 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
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 activate a socket. It MUST be silently ignored by a
recipient. recipient.
3.8. 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.
3.8.1. 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 are usually scoped by using encapsulation. However,
this is not a requirement this is not a requirement
3.8.2. 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.
A discovery initiator MAY ignore a Divert option if it only requires A discovery initiator MAY ignore a Divert option if it only requires
direct discovery responses. direct discovery responses.
In fragmentary CDDL, the Divert option follows the pattern: In fragmentary CDDL, the Divert option follows the pattern:
divert-option = [O_DIVERT, +locator-option] divert-option = [O_DIVERT, +locator-option]
The embedded Locator Option(s) (Section 3.8.5) point to diverted The embedded Locator Option(s) (Section 3.9.5) point to diverted
destination target(s) in response to a Discovery message. destination target(s) in response to a Discovery message.
3.8.3. Accept Option 3.9.3. Accept Option
The accept option is used to indicate to the negotiation counterpart The accept option is used to indicate to the negotiation counterpart
that the proposed negotiation content is accepted. that the proposed negotiation content is accepted.
The accept option MUST only be encapsulated in Negotiation End The accept option MUST only be encapsulated in Negotiation End
messages. If found elsewhere, it SHOULD be silently ignored. messages. If found elsewhere, it SHOULD be silently ignored.
In fragmentary CDDL, the Accept option follows the pattern: In fragmentary CDDL, the Accept option follows the pattern:
accept-option = [O_ACCEPT] accept-option = [O_ACCEPT]
3.8.4. Decline Option 3.9.4. Decline Option
The decline option is used to indicate to the negotiation counterpart The decline option is used to indicate to the negotiation counterpart
the proposed negotiation content is declined and end the negotiation the proposed negotiation content is declined and end the negotiation
process. process.
The decline option MUST only be encapsulated in Negotiation End The decline option MUST only be encapsulated in Negotiation End
messages. If found elsewhere, it SHOULD be silently ignored. messages. If found elsewhere, it SHOULD be silently ignored.
In fragmentary CDDL, the Decline option follows the pattern: In fragmentary CDDL, the Decline option follows the pattern:
decline-option = [O_DECLINE, ?reason] decline-option = [O_DECLINE, ?reason]
reason = text ;optional error message reason = text ;optional error message
Note: there are scenarios where a negotiation counterpart wants to Note: there are scenarios where a negotiation counterpart wants to
decline the proposed negotiation content and continue the negotiation decline the proposed negotiation content and continue the negotiation
process. For these scenarios, the negotiation counterpart SHOULD use process. For these scenarios, the negotiation counterpart SHOULD use
a Negotiate message, with either an objective option that contains a a Negotiate message, with either an objective option that contains a
data field set to indicate a meaningless initial value, or a specific data field set to indicate a meaningless initial value, or a specific
objective option that provides further conditions for convergence. objective option that provides further conditions for convergence.
3.8.5. 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
protocol and port number for reaching the target. For this reason, protocol and port number for reaching the target. For this reason,
the Locator Options for IP addresses and FQDNs include this the Locator Options for IP addresses and FQDNs include this
information explicitly. In the case of the URI Option, this information explicitly. In the case of the URI Option, this
information can be encoded in the URI itself. information can be encoded in the URI itself.
Note: It is assumed that all locators are in scope throughout the Note: It is assumed that all locators are in scope throughout the
GRASP domain. GRASP is not intended to work across disjoint GRASP domain. GRASP is not intended to work across disjoint
addressing or naming realms. addressing or naming realms.
3.8.5.1. Locator IPv6 address option 3.9.5.1. Locator IPv6 address option
In fragmentary CDDL, the IPv6 address option follows the pattern: In fragmentary CDDL, the IPv6 address option follows the pattern:
ipv6-locator-option = [O_IPv6_LOCATOR, ipv6-address, ipv6-locator-option = [O_IPv6_LOCATOR, ipv6-address,
transport-proto, port-number] transport-proto, port-number]
ipv6-address = bytes .size 16 ipv6-address = bytes .size 16
transport-proto = IPPROTO_TCP / IPPROTO_UDP transport-proto = IPPROTO_TCP / IPPROTO_UDP
IPPROTO_TCP = 6 IPPROTO_TCP = 6
IPPROTO_UDP = 17 IPPROTO_UDP = 17
skipping to change at page 35, line 28 skipping to change at page 38, line 12
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.
Exceptionally, during node bootstrap, a link-local address MAY be Exceptionally, during node bootstrap, a link-local address MAY be
used for specific objectives only. used for specific objectives only.
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.
3.8.5.2. 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]
ipv4-address = bytes .size 4 ipv4-address = bytes .size 4
The content of this option is a binary IPv4 address followed by the The content of this option is a binary IPv4 address followed by the
protocol number and port number to be used. protocol number and port number to be used.
Note: If an operator has internal network address translation for Note: If an operator has internal network address translation for
IPv4, this option MUST NOT be used within the Divert option. IPv4, this option MUST NOT be used within the Divert option.
3.8.5.3. Locator FQDN option 3.9.5.3. Locator FQDN option
In fragmentary CDDL, the FQDN option follows the pattern: In fragmentary CDDL, the FQDN option follows the pattern:
fqdn-locator-option = [O_FQDN_LOCATOR, text, fqdn-locator-option = [O_FQDN_LOCATOR, text,
transport-proto, port-number] transport-proto, port-number]
The content of this option is the Fully Qualified Domain Name of the The content of this option is the Fully Qualified Domain Name of the
target followed by the protocol number and port number to be used. target followed by the protocol number and port number to be used.
Note 1: Any FQDN which might not be valid throughout the network in Note 1: Any FQDN which might not be valid throughout the network in
question, such as a Multicast DNS name [RFC6762], MUST NOT be used question, such as a Multicast DNS name [RFC6762], MUST NOT be used
when this option is used within the Divert option. when this option is used within the Divert option.
Note 2: Normal GRASP operations are not expected to use this option. Note 2: Normal GRASP operations are not expected to use this option.
It is intended for special purposes such as discovering external It is intended for special purposes such as discovering external
services. services.
3.8.5.4. Locator URI option 3.9.5.4. Locator URI option
In fragmentary CDDL, the URI option follows the pattern: In fragmentary CDDL, the URI option follows the pattern:
uri-locator = [O_URI_LOCATOR, text] uri-locator = [O_URI_LOCATOR, text]
The content of this option is the Uniform Resource Identifier of the The content of this option is the Uniform Resource Identifier of the
target [RFC3986]. target [RFC3986].
Note 1: Any URI which might not be valid throughout the network in Note 1: Any URI which might not be valid throughout the network in
question, such as one based on a Multicast DNS name [RFC6762], MUST question, such as one based on a Multicast DNS name [RFC6762], MUST
NOT be used when this option is used within the Divert option. NOT be used when this option is used within the Divert option.
Note 2: Normal GRASP operations are not expected to use this option. Note 2: Normal GRASP operations are not expected to use this option.
It is intended for special purposes such as discovering external It is intended for special purposes such as discovering external
services. services.
3.9. Objective Options 3.10. Objective Options
3.9.1. Format of Objective Options 3.10.1. Format of Objective Options
An objective option is used to identify objectives for the purposes An objective option is used to identify objectives for the purposes
of discovery, negotiation or synchronization. All objectives MUST be of discovery, negotiation or synchronization. All objectives MUST be
in the following format, described in fragmentary CDDL: in the following format, described in fragmentary CDDL:
objective = [objective-name, objective-flags, loop-count, ?any] objective = [objective-name, objective-flags, loop-count, ?any]
objective-name = text objective-name = text
loop-count = 0..255 loop-count = 0..255
skipping to change at page 37, line 24 skipping to change at page 40, line 6
3. The unique string is an email address that uniquely identifies 3. The unique string is an email address that uniquely identifies
the entity or person defining the objective. the entity or person defining the objective.
The GRASP protocol treats the objective name as an opaque string. The GRASP protocol treats the objective name as an opaque string.
For example, "EX1", "411:EX1", "example.com:EX1", "example.org:EX1 For example, "EX1", "411:EX1", "example.com:EX1", "example.org:EX1
and "user@example.org:EX1" would be five different objectives. and "user@example.org:EX1" would be five different objectives.
The 'objective-flags' field is described below. The 'objective-flags' field is described below.
The 'loop-count' field is used for terminating negotiation as The 'loop-count' field is used for terminating negotiation as
described in Section 3.7.6. It is also used for terminating described in Section 3.8.7. It is also used for terminating
discovery as described in Section 3.3.4, and for terminating flooding discovery as described in Section 3.5.4, and for terminating flooding
as described in Section 3.3.6.1. as described in Section 3.5.6.1.
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 single 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.
3.9.2. 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 flags: in the objective by logical flags:
objective-flags = uint .bits objective-flag objective-flags = uint .bits objective-flag
objective-flag = &( objective-flag = &(
F_DISC: 0 ; valid for discovery only F_DISC: 0 ; valid for discovery only
F_NEG: 1 ; valid for discovery and negotiation F_NEG: 1 ; valid for discovery and negotiation
F_SYNCH: 2 ; valid for discovery and synchronization F_SYNCH: 2 ; valid for discovery and synchronization
) )
3.9.3. General Considerations for Objective Options 3.10.3. General Considerations for Objective Options
As mentioned above, Objective Options MUST be assigned a unique name. As mentioned above, Objective Options MUST be assigned a unique name.
As long as privately defined Objective Options obey the rules above, As long as privately defined Objective Options obey the rules above,
this document does not restrict their choice of name, but the entity this document does not restrict their choice of name, but the entity
or person concerned SHOULD publish the names in use. or person concerned SHOULD publish the names in use.
All Objective Options MUST respect the CBOR patterns defined above as All Objective Options MUST respect the CBOR patterns defined above as
"objective" and MUST replace the "any" field with a valid CBOR data "objective" and MUST replace the "any" field with a valid CBOR data
definition for the relevant use case and application. definition for the relevant use case and application.
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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 bits in the value field SHOULD all be set to indicate a
meaningless value, unless this is inappropriate for the specific meaningless value, unless this is inappropriate for the specific
negotiation objective. 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.
3.9.4. 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
the synchronization mechanism described above. the synchronization mechanism described above.
As noted earlier, one negotiation objective is handled by each GRASP As noted earlier, one negotiation objective is handled by each GRASP
negotiation thread. Therefore, a negotiation objective, which is negotiation thread. Therefore, a negotiation objective, which is
based on a specific function or action, SHOULD be organized as a based on a specific function or action, SHOULD be organized as a
single GRASP option. It is NOT RECOMMENDED to organize multiple single GRASP option. It is NOT RECOMMENDED to organize multiple
negotiation objectives into a single option, nor to split a single negotiation objectives into a single option, nor to split a single
skipping to change at page 39, line 35 skipping to change at page 42, line 15
for the specifications of individual objectives. There are many for the specifications of individual objectives. There are many
candidates, according to the context, such as ABNF, RBNF, XML Schema, candidates, according to the context, such as ABNF, RBNF, XML Schema,
possibly YANG, etc. The GRASP protocol itself is agnostic on these possibly YANG, etc. The GRASP protocol itself is agnostic on these
questions. questions.
It is NOT RECOMMENDED to split parameters in a single objective into It is NOT RECOMMENDED to split parameters in a single objective into
multiple options, unless they have different response periods. An multiple options, unless they have different response periods. An
exception scenario may also be described by split objectives. exception scenario may also be described by split objectives.
All objectives MUST support GRASP discovery. However, as mentioned All objectives MUST support GRASP discovery. However, as mentioned
in Section 3.2, 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
the ACP. the ACP.
3.9.5. Experimental and Example Objective Options 3.10.5. Experimental and Example Objective Options
The names "EX0" through "EX9" have been reserved for experimental The names "EX0" through "EX9" have been reserved for experimental
options. Multiple names have been assigned because a single options. Multiple names have been assigned because a single
experiment may use multiple options simultaneously. These experiment may use multiple options simultaneously. These
experimental options are highly likely to have different meanings experimental options are highly likely to have different meanings
when used for different experiments. Therefore, they SHOULD NOT be when used for different experiments. Therefore, they SHOULD NOT be
used without an explicit human decision and SHOULD NOT be used in used without an explicit human decision and SHOULD NOT be used in
unmanaged networks such as home networks. unmanaged networks such as home networks.
These names are also RECOMMENDED for use in documentation examples. These names are also RECOMMENDED for use in documentation examples.
skipping to change at page 40, line 49 skipping to change at page 43, line 30
o Contact: https://github.com/liubingpang/IETF-Anima-Signaling- o Contact: https://github.com/liubingpang/IETF-Anima-Signaling-
Protocol Protocol
4.2. Python Implementation 4.2. Python Implementation
o Name: graspy o Name: graspy
o Description: Python 3 implementation of GRASP kernel and API. o Description: Python 3 implementation of GRASP kernel and API.
o Maturity: Prototype code, interoperable between Windows 7 and o Maturity: Prototype code, interoperable between Windows 7 and
Debian. Linux.
o Coverage: Corresponds to draft-ietf-anima-grasp-07. Limitations o Coverage: Corresponds to draft-ietf-anima-grasp-08. 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 42, line 11 skipping to change at page 44, line 38
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 is intended to be deployed in a single administrative
domain operating its own trust anchor and CA, there is no need for domain operating its own trust anchor and CA, there is no need for
a trusted public third party. In a network requiring "air gap" a trusted public third party. In a network requiring "air gap"
security, such a dependency would be unacceptable. 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 3.3.1), mechanism, for example during system bootstrap (Section 3.5.1),
the Session ID (Section 3.6) 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 out of scope for
the present document. the present document.
- Authorization and Roles - Authorization and Roles
The GRASP protocol is agnostic about the role of individual ASAs The GRASP protocol is agnostic about the role of individual ASAs
and about which objectives a particular ASA is authorized to and about which objectives a particular ASA is authorized to
support. An implementation might support precautions such as support. An implementation might support precautions such as
allowing only one ASA in a given node to modify a given objective, allowing only one ASA in a given node to modify a given objective,
skipping to change at page 42, line 38 skipping to change at page 45, line 17
- 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
a large network, the security mechanism for the protocol MUST a large network, the security mechanism for the protocol MUST
provide message confidentiality. This is why Section 3.3.1 provide message confidentiality. This is why Section 3.5.1
requires either an ACP or the use of TLS. requires either an ACP or the use of TLS.
- Link-local multicast security - Link-local multicast security
GRASP has no reasonable alternative to using link-local multicast GRASP has no reasonable alternative to using link-local multicast
for Discovery or Flood Synchronization messages and these messages for Discovery or Flood Synchronization messages and these messages
are sent in clear and with no authentication. They are 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 3.3.1), 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 3.3.6.1. messages are suggested in Section 3.5.6.1.
- 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. Relevant mitigations are specified in denial of service attacks. Some mitigations are specified in
Section 3.3.4. Additionally, it is of great importance that Section 3.5.4. However, malicious code installed inside the
firewalls prevent any GRASP messages from entering the domain from Autonomic Control Plane could always launch DoS attacks consisting
an untrusted source. of spurious discovery messages, or of spurious discovery
responses. Additionally, it is of great importance that firewalls
prevent any GRASP messages from entering the domain from an
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 authenticate GRASP traffic from other nodes until it
has identified the trust anchor and can validate certificates for has identified the trust anchor and can validate 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] it 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 and GRASP 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 3.3.2. 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 3.3.1). 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
message-structure = [MESSAGE_TYPE, session-id, ?initiator, message-structure = [MESSAGE_TYPE, session-id, ?initiator,
*grasp-option] *grasp-option]
MESSAGE_TYPE = 0..255 MESSAGE_TYPE = 0..255
session-id = 0..16777215 ;up to 24 bits session-id = 0..4294967295 ;up to 32 bits
grasp-option = any grasp-option = any
message /= discovery-message message /= discovery-message
discovery-message = [M_DISCOVERY, session-id, initiator, objective] discovery-message = [M_DISCOVERY, session-id, initiator, objective]
message /= response-message ;response to Discovery message /= response-message ;response to Discovery
response-message = [M_RESPONSE, session-id, initiator, ttl, response-message = [M_RESPONSE, session-id, initiator, ttl,
(+locator-option // divert-option), ?objective] (+locator-option // divert-option), ?objective]
message /= synch-message ;response to Synchronization request message /= synch-message ;response to Synchronization request
skipping to change at page 44, line 22 skipping to change at page 47, line 4
(locator-option / []), +objective] (locator-option / []), +objective]
message /= request-negotiation-message message /= request-negotiation-message
request-negotiation-message = [M_REQ_NEG, session-id, objective] request-negotiation-message = [M_REQ_NEG, session-id, objective]
message /= request-synchronization-message message /= request-synchronization-message
request-synchronization-message = [M_REQ_SYN, session-id, objective] request-synchronization-message = [M_REQ_SYN, session-id, objective]
message /= negotiation-message message /= negotiation-message
negotiation-message = [M_NEGOTIATE, session-id, objective] negotiation-message = [M_NEGOTIATE, session-id, objective]
message /= end-message message /= end-message
end-message = [M_END, session-id, accept-option / decline-option ] end-message = [M_END, session-id, accept-option / decline-option ]
message /= wait-message message /= wait-message
wait-message = [M_WAIT, session-id, waiting-time] wait-message = [M_WAIT, session-id, waiting-time]
message /= invalid-message
invalid-message = [M_INVALID, session-id, ?any]
noop-message = [M_NOOP] noop-message = [M_NOOP]
divert-option = [O_DIVERT, +locator-option] divert-option = [O_DIVERT, +locator-option]
accept-option = [O_ACCEPT] accept-option = [O_ACCEPT]
decline-option = [O_DECLINE, ?reason] decline-option = [O_DECLINE, ?reason]
reason = text ;optional error message reason = text ;optional error message
waiting-time = 0..4294967295 ; in milliseconds waiting-time = 0..4294967295 ; in milliseconds
skipping to change at page 45, line 37 skipping to change at page 48, line 20
M_NOOP = 0 M_NOOP = 0
M_DISCOVERY = 1 M_DISCOVERY = 1
M_RESPONSE = 2 M_RESPONSE = 2
M_REQ_NEG = 3 M_REQ_NEG = 3
M_REQ_SYN = 4 M_REQ_SYN = 4
M_NEGOTIATE = 5 M_NEGOTIATE = 5
M_END = 6 M_END = 6
M_WAIT = 7 M_WAIT = 7
M_SYNCH = 8 M_SYNCH = 8
M_FLOOD = 9 M_FLOOD = 9
M_INVALID = 99
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
<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 3.5 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_NEIGHBOR 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_NEIGHBOR multicast address (IPv4): (TBD2). Assigned in
the IPv4 Multicast Local Network Control Block. the IPv4 Multicast Local Network Control Block.
Section 3.5 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
Description: See Section 3.5 Description: See Section 3.6
Reference: RFC XXXX (this document) Reference: RFC XXXX (this document)
The IANA is requested to create a GRASP Parameter Registry including The IANA is requested to create a GRASP Parameter Registry including
two registry tables. These are the GRASP Messages and Options two registry tables. These are the GRASP Messages and Options
Table and the GRASP Objective Names Table. Table and the GRASP Objective Names Table.
GRASP Messages and Options Table. The values in this table are names GRASP Messages and Options Table. The values in this table are names
paired with decimal integers. Future values MUST be assigned using paired with decimal integers. Future values MUST be assigned using
the Standards Action policy defined by [RFC5226]. The following the Standards Action policy defined by [RFC5226]. The following
initial values are assigned by this document: initial values are assigned by this document:
skipping to change at page 46, line 44 skipping to change at page 49, line 27
M_NOOP = 0 M_NOOP = 0
M_DISCOVERY = 1 M_DISCOVERY = 1
M_RESPONSE = 2 M_RESPONSE = 2
M_REQ_NEG = 3 M_REQ_NEG = 3
M_REQ_SYN = 4 M_REQ_SYN = 4
M_NEGOTIATE = 5 M_NEGOTIATE = 5
M_END = 6 M_END = 6
M_WAIT = 7 M_WAIT = 7
M_SYNCH = 8 M_SYNCH = 8
M_FLOOD = 9 M_FLOOD = 9
M_INVALID = 99
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]. The following initial values
are assigned by this document: are assigned by this document:
EX0 EX0
EX1 EX1
EX2 EX2
EX3 EX3
EX4 EX4
skipping to change at page 47, line 23 skipping to change at page 50, line 8
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. made by Sheng Jiang. Significant review inputs were received from
Joel Halpern 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, Toerless Eckert, Yu Fu, Campos Nobre, Laurent Ciavaglia, Zongpeng Du, Toerless Eckert, Yu Fu,
Joel Halpern, Zhenbin Li, Dimitri Papadimitriou, Pierre Peloso, Zhenbin Li, Dimitri Papadimitriou, Pierre Peloso, Reshad Rahman,
Reshad Rahman, Michael Richardson, Markus Stenberg, Rene Struik, Markus Stenberg, Rene Struik, Dacheng Zhang, and other participants
Dacheng Zhang, and other participants in the NMRG research group and in the NMRG research group and the ANIMA working group.
the ANIMA working group.
9. References 9. References
9.1. Normative References 9.1. Normative References
[I-D.greevenbosch-appsawg-cbor-cddl] [I-D.greevenbosch-appsawg-cbor-cddl]
Vigano, C. and H. Birkholz, "CBOR data definition language Vigano, C. and H. Birkholz, "CBOR data definition language
(CDDL): a notational convention to express CBOR data (CDDL): a notational convention to express CBOR data
structures", draft-greevenbosch-appsawg-cbor-cddl-08 (work structures", draft-greevenbosch-appsawg-cbor-cddl-09 (work
in progress), March 2016. in progress), September 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>. <http://www.rfc-editor.org/info/rfc3986>.
skipping to change at page 49, line 19 skipping to change at page 52, line 7
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-01 (work in progress), July
2016. 2016.
[I-D.ietf-netconf-restconf] [I-D.ietf-netconf-restconf]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", draft-ietf-netconf-restconf-16 (work in Protocol", draft-ietf-netconf-restconf-18 (work in
progress), August 2016. 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]
Carpenter, B., Liu, B., Wang, W., and X. Gong, "Generic
Autonomic Signaling Protocol Application Program Interface
(GRASP API)", draft-liu-anima-grasp-api-02 (work in
progress), September 2016.
[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 51, line 44 skipping to change at page 54, line 40
<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 Appendix A. Open Issues [RFC Editor: Please remove if empty]
o 7. Cross-check against other ANIMA WG documents for consistency o 59. Placeholder.
and gaps.
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 53, line 37 skipping to change at page 56, line 28
node starts up, performs discovery, and conducts negotiation and node starts up, performs discovery, and conducts negotiation and
synchronisation for a sample use case would help readers to synchronisation for a sample use case would help readers to
understand the applicability of this specification. Maybe it understand the applicability of this specification. Maybe it
should be an artificial use case or maybe a simple real one, based should be an artificial use case or maybe a simple real one, based
on a conceptual API. However, the authors have not yet decided on a conceptual API. However, the authors have not yet decided
whether to have a separate document or have it in the protocol whether to have a separate document or have it in the protocol
document. document.
RESOLVED: recommend a separate document. RESOLVED: recommend a separate document.
o 7. Cross-check against other ANIMA WG documents for consistency
and gaps.
RESOLVED: Satisfied by WGLC.
o 8. Consideration of ADNCP proposal. o 8. Consideration of ADNCP proposal.
RESOLVED by adding optional use of DNCP for flooding-type RESOLVED by adding optional use of DNCP for flooding-type
synchronization. synchronization.
o 9. Clarify how a GDNP instance knows whether it is running inside o 9. Clarify how a GDNP instance knows whether it is running inside
the ACP. (Sheng) the ACP. (Sheng)
RESOLVED by improved text. RESOLVED by improved text.
skipping to change at page 55, line 51 skipping to change at page 58, line 48
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 3.3.6.1). o 27. Security of Flood multicasts (Section 3.5.6.1).
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.
RESOLVED: Simplified this by removing PEN field and changing RESOLVED: Simplified this by removing PEN field and changing
naming rules for objectives. naming rules for objectives.
o 30. Does response to discovery require randomized delays to o 30. Does response to discovery require randomized delays to
mitigate amplification attacks? mitigate amplification attacks?
skipping to change at page 58, line 32 skipping to change at page 61, line 29
two different messages (and adjust various message names two different messages (and adjust various message names
accordingly)? accordingly)?
RESOLVED: Yes. Done. RESOLVED: Yes. Done.
o 48. Should the Appendix "Capability Analysis of Current o 48. Should the Appendix "Capability Analysis of Current
Protocols" be deleted before RFC publication? Protocols" be deleted before RFC publication?
RESOLVED: No (per WG meeting at IETF 96). RESOLVED: No (per WG meeting at IETF 96).
o 49. Section 3.3.1 Should say more about signaling between two o 49. Section 3.5.1 Should say more about signaling between two
autonomic networks/domains. autonomic networks/domains.
RESOLVED: Description of separate GRASP instance added. RESOLVED: Description of separate GRASP instance added.
o 50. Is Rapid mode limited to on-link only? What happens if first o 50. Is Rapid mode limited to on-link only? What happens if first
discovery responder does not support Rapid Mode? Section 3.3.5, discovery responder does not support Rapid Mode? Section 3.5.5,
Section 3.3.6) Section 3.5.6)
RESOLVED: Not limited to on-link. First responder wins. RESOLVED: Not limited to on-link. First responder wins.
o 51. Should flooded objectives have a time-to-live before they are o 51. Should flooded objectives have a time-to-live before they are
deleted from the flood cache? And should they be tagged in the deleted from the flood cache? And should they be tagged in the
cache with their source locator? cache with their source locator?
RESOLVED: TTL added to Flood (and Discovery Response) messages. RESOLVED: TTL added to Flood (and Discovery Response) messages.
Cached flooded objectives must be tagged with their originating Cached flooded objectives must be tagged with their originating
ASA locator, and multiple copies must be kept if necessary. ASA locator, and multiple copies must be kept if necessary.
o 52. Describe in detail what is allowed and disallowed in an o 52. Describe in detail what is allowed and disallowed in an
insecure instance of GRASP. insecure instance of GRASP.
RESOLVED: Done. RESOLVED: Done.
o 53. Tune IANA Considerations to support early assignment request. o 53. Tune IANA Considerations to support early assignment request.
o 54. Is there a highly unlikely race condition if two peers
simultaneously choose the same Session ID and send each other
simultaneous M_REQ_NEG messages?
RESOLVED: Yes. Enhanced text on Session ID generation, and added
precaution when receiving a Request message.
o 55. Could discovery be performed over TCP?
RESOLVED: Unicast discovery added as an option.
o 56. Change Session-ID to 32 bits?
RESOLVED: Done. RESOLVED: Done.
o 57. Add M_INVALID message?
RESOLVED: Done.
o 58. Maximum message size?
RESOLVED by specifying default maximum message size (2048 bytes).
Appendix C. Change log [RFC Editor: Please remove] Appendix C. Change log [RFC Editor: Please remove]
draft-ietf-anima-grasp-08, 2016-10-30:
Protocol change: Added M_INVALID message.
Protocol change: Increased Session ID space to 32 bits.
Enhanced rules to avoid Session ID clashes.
Corrected and completed description of timeouts for Request messages.
Improved wording about exponential backoff and DoS.
Clarified that discovery relaying is not done by limited security
instances.
Corrected and expanded explanation of port used for Discovery
Response.
Noted that Discovery message could be sent unicast in special cases.
Added paragraph on extensibility.
Specified default maximum message size.
Added Appendix for sample messages.
Added short protocol overview.
Editorial fixes, including minor re-ordering for readability.
draft-ietf-anima-grasp-07, 2016-09-13: draft-ietf-anima-grasp-07, 2016-09-13:
Protocol change: Added TTL field to Flood message (issue 51). Protocol change: Added TTL field to Flood message (issue 51).
Protocol change: Added Locator option to Flood message (issue 51). Protocol change: Added Locator option to Flood message (issue 51).
Protocol change: Added TTL field to Discovery Response message Protocol change: Added TTL field to Discovery Response message
(corrollary to issue 51). (corrollary to issue 51).
Clarified details of rapid mode (issues 43 and 50). Clarified details of rapid mode (issues 43 and 50).
skipping to change at page 63, line 40 skipping to change at page 67, line 41
draft-carpenter-anima-gdn-protocol-01, restructured the logical flow draft-carpenter-anima-gdn-protocol-01, restructured the logical flow
of the document, updated to describe synchronization completely, add of the document, updated to describe synchronization completely, add
unsolicited responses, numerous corrections and clarifications, unsolicited responses, numerous corrections and clarifications,
expanded future work list, 2015-01-06. expanded future work list, 2015-01-06.
draft-carpenter-anima-gdn-protocol-00, combination of draft-jiang- draft-carpenter-anima-gdn-protocol-00, combination of draft-jiang-
config-negotiation-ps-03 and draft-jiang-config-negotiation-protocol- config-negotiation-ps-03 and draft-jiang-config-negotiation-protocol-
02, 2014-10-08. 02, 2014-10-08.
Appendix D. Capability Analysis of Current Protocols Appendix D. Example Message Formats
For readers unfamiliar with CBOR, this appendix shows a number of
example GRASP messages conforming to the CDDL syntax given in
Section 6. Each message is shown three times in the following
formats:
1. CBOR diagnostic notation.
2. Similar, but showing the names of the constants.
3. Hexadecimal version of the CBOR wire format.
Long lines are split for display purposes only.
D.1. Discovery Example
The initiator multicasts a discovery message:
[1, 13948744, h'20010db8f000baaa28ccdc4c97036781', ["EX1", 2, 2, 0]]
[M_DISCOVERY, 13948744, h'20010db8f000baaa28ccdc4c97036781',
["EX1", F_SYNCH, 2, 0]]
h'84011a00d4d7485020010db8f000baaa28ccdc4c970367818463455831020200'
A peer responds with a locator:
[2, 13948744, h'20010db8f000baaa28ccdc4c97036781', 60000,
[103, h'20010db8f000baaaf000baaaf000baaa', 6, 49443]]
[M_RESPONSE, 13948744, h'20010db8f000baaa28ccdc4c97036781', 60000,
[O_IPv6_LOCATOR, h'20010db8f000baaaf000baaaf000baaa',
IPPROTO_TCP, 49443]]
h'85021a00d4d7485020010db8f000baaa28ccdc4c9703678119ea6084186750
20010db8f000baaaf000baaaf000baaa0619c123'
D.2. Flood Example
The initiator multicasts a flood message. There is no response:
[9, 3504974, h'20010db8f000baaa28ccdc4c97036781', 10000, [],
["EX1", 2, 2, ["Example 1 value=", 100]]]
[M_FLOOD, 3504974, h'20010db8f000baaa28ccdc4c97036781', 10000, [],
["EX1", F_SYNCH, 2, ["Example 1 value=", 100]]]
h'86091a00357b4e5020010db8f000baaa28ccdc4c9703678119271080846345
5831020282704578616d706c6520312076616c75653d1864'
D.3. Synchronization Example
The initiator unicasts a request:
[4, 4038926, ["EX2", 2, 5, 0]]
[M_REQ_SYN, 4038926, ["EX2", F_SYNCH, 5, 0]]
h'83041a003da10e8463455832020500'
The peer responds with a value:
[8, 4038926, ["EX2", 2, 5, ["Example 2 value=", 200]]]
[M_SYNCH, 4038926, ["EX2", F_SYNCH, 5, ["Example 2 value=", 200]]]
h'83081a003da10e8463455832020582704578616d706c6520322076616c75653d18c8'
D.4. Simple Negotiation Example
The initiator unicasts a request:
[3, 802813, ["EX3", 1, 6, ["NZD", 47]]]
[M_REQ_NEG, 802813, ["EX3", 1, 6, ["NZD", 47]]]
h'83031a000c3ffd8463455833010682634e5a44182f'
The peer responds with immediate acceptance. Note that no objective
is needed, because the initiator's request was accepted without
change:
[6, 802813, [101]]
[M_END , 802813, [O_ACCEPT]]
h'83061a000c3ffd811865'
D.5. Complete Negotiation Example
The initiator unicasts a request:
[3, 13767778, ["EX3", 1, 6, ["NZD", 410]]]
[M_REQ_NEG, 13767778, ["EX3", F_NEG, 6, ["NZD", 410]]]
h'83031a00d214628463455833010682634e5a4419019a'
The responder starts to negotiate (making an offer):
[5, 13767778, ["EX3", 1, 6, ["NZD", 80]]]
[M_NEGOTIATE, 13767778, ["EX3", F_NEG, 6, ["NZD", 80]]]
h'83051a00d214628463455833010682634e5a441850'
The initiator continues to negotiate (reducing its request):
[5, 13767778, ["EX3", 1, 5, ["NZD", 307]]]
[M_NEGOTIATE, 13767778, ["EX3", F_NEG, 5, ["NZD", 307]]]
h'83051a00d214628463455833010582634e5a44190133'
The responder asks for more time:
[7, 13767778, 34965]
[M_WAIT, 13767778, 34965]
h'83071a00d21462198895'
The responder continues to negotiate (increasing its offer):
[5, 13767778, ["EX3", 1, 4, ["NZD", 120]]]
[M_NEGOTIATE, 13767778, ["EX3", F_NEG, 4, ["NZD", 120]]]
h'83051a00d214628463455833010482634e5a441878'
The initiator continues to negotiate (reducing its request):
[5, 13767778, ["EX3", 1, 3, ["NZD", 246]]]
[M_NEGOTIATE, 13767778, ["EX3", F_NEG, 3, ["NZD", 246]]]
h'83051a00d214628463455833010382634e5a4418f6'
The responder refuses to negotiate further:
[6, 13767778, [102, "Insufficient funds"]]
[M_END , 13767778, [O_DECLINE, "Insufficient funds"]]
h'83061a00d2146282186672496e73756666696369656e742066756e6473'
This negotiation has failed. If either side had sent [M_END,
13767778, [O_ACCEPT]] it would have succeeded, converging on the
objective value in the preceding M_NEGOTIATE. Note that apart from
the initial M_REQ_NEG, the process is symmetrical.
Appendix E. Capability Analysis of Current Protocols
This appendix discusses various existing protocols with properties This appendix discusses various existing protocols with properties
related to the requirements described in Section 2. The purpose is related to the requirements described in Section 2. The purpose is
to evaluate whether any existing protocol, or a simple combination of to evaluate whether any existing protocol, or a simple combination of
existing protocols, can meet those requirements. existing protocols, can meet those requirements.
Numerous protocols include some form of discovery, but these all Numerous protocols include some form of discovery, but these all
appear to be very specific in their applicability. Service Location appear to be very specific in their applicability. Service Location
Protocol (SLP) [RFC2608] provides service discovery for managed Protocol (SLP) [RFC2608] provides service discovery for managed
networks, but requires configuration of its own servers. DNS-SD networks, but requires configuration of its own servers. DNS-SD
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