draft-ietf-anima-grasp-06.txt   draft-ietf-anima-grasp-07.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: December 29, 2016 Univ. of Auckland Expires: March 17, 2017 Univ. of Auckland
B. Liu, Ed. B. Liu, Ed.
Huawei Technologies Co., Ltd Huawei Technologies Co., Ltd
June 27, 2016 September 13, 2016
A Generic Autonomic Signaling Protocol (GRASP) A Generic Autonomic Signaling Protocol (GRASP)
draft-ietf-anima-grasp-06 draft-ietf-anima-grasp-07
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
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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 December 29, 2016. This Internet-Draft will expire on March 17, 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
skipping to change at page 2, line 25 skipping to change at page 2, line 25
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 . . . . . . . . . . . . . 8
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 Design Choices . . . . . . . . . . . . . . . . 11
3.3. GRASP Protocol Basic Properties and Mechanisms . . . . . 15 3.3. GRASP Protocol Basic Properties and Mechanisms . . . . . 15
3.3.1. Required External Security Mechanism . . . . . . . . 15 3.3.1. Required External Security Mechanism . . . . . . . . 15
3.3.2. Transport Layer Usage . . . . . . . . . . . . . . . . 16 3.3.2. Limited Security Instances . . . . . . . . . . . . . 15
3.3.3. Discovery Mechanism and Procedures . . . . . . . . . 16 3.3.3. Transport Layer Usage . . . . . . . . . . . . . . . . 17
3.3.4. Negotiation Procedures . . . . . . . . . . . . . . . 20 3.3.4. Discovery Mechanism and Procedures . . . . . . . . . 18
3.3.5. Synchronization and Flooding Procedure . . . . . . . 21 3.3.5. Negotiation Procedures . . . . . . . . . . . . . . . 21
3.4. High Level Deployment Model . . . . . . . . . . . . . . . 23 3.3.6. Synchronization and Flooding Procedure . . . . . . . 22
3.5. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 24 3.4. High Level Deployment Model . . . . . . . . . . . . . . . 24
3.6. Session Identifier (Session ID) . . . . . . . . . . . . . 24 3.5. GRASP Constants . . . . . . . . . . . . . . . . . . . . . 25
3.7. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 25 3.6. Session Identifier (Session ID) . . . . . . . . . . . . . 26
3.7.1. Message Overview . . . . . . . . . . . . . . . . . . 25 3.7. GRASP Messages . . . . . . . . . . . . . . . . . . . . . 26
3.7.2. GRASP Message Format . . . . . . . . . . . . . . . . 25 3.7.1. Message Overview . . . . . . . . . . . . . . . . . . 26
3.7.3. Discovery Message . . . . . . . . . . . . . . . . . . 26 3.7.2. GRASP Message Format . . . . . . . . . . . . . . . . 27
3.7.4. Discovery Response Message . . . . . . . . . . . . . 27 3.7.3. Discovery Message . . . . . . . . . . . . . . . . . . 27
3.7.5. Request Messages . . . . . . . . . . . . . . . . . . 27 3.7.4. Discovery Response Message . . . . . . . . . . . . . 28
3.7.6. Negotiation Message . . . . . . . . . . . . . . . . . 28 3.7.5. Request Messages . . . . . . . . . . . . . . . . . . 29
3.7.7. Negotiation End Message . . . . . . . . . . . . . . . 28 3.7.6. Negotiation Message . . . . . . . . . . . . . . . . . 30
3.7.8. Confirm Waiting Message . . . . . . . . . . . . . 29 3.7.7. Negotiation End Message . . . . . . . . . . . . . . . 30
3.7.9. Synchronization Message . . . . . . . . . . . . . . . 29 3.7.8. Confirm Waiting Message . . . . . . . . . . . . . 31
3.7.10. Flood Synchronization Message . . . . . . . . . . . . 29 3.7.9. Synchronization Message . . . . . . . . . . . . . . . 31
3.7.11. No Operation Message . . . . . . . . . . . . . . . . 30 3.7.10. Flood Synchronization Message . . . . . . . . . . . . 31
3.8. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 30 3.7.11. No Operation Message . . . . . . . . . . . . . . . . 32
3.8.1. Format of GRASP Options . . . . . . . . . . . . . . . 30 3.8. GRASP Options . . . . . . . . . . . . . . . . . . . . . . 33
3.8.2. Divert Option . . . . . . . . . . . . . . . . . . . . 30 3.8.1. Format of GRASP Options . . . . . . . . . . . . . . . 33
3.8.3. Accept Option . . . . . . . . . . . . . . . . . . . . 31 3.8.2. Divert Option . . . . . . . . . . . . . . . . . . . . 33
3.8.4. Decline Option . . . . . . . . . . . . . . . . . . . 31 3.8.3. Accept Option . . . . . . . . . . . . . . . . . . . . 33
3.8.5. Locator Options . . . . . . . . . . . . . . . . . . . 31 3.8.4. Decline Option . . . . . . . . . . . . . . . . . . . 34
3.9. Objective Options . . . . . . . . . . . . . . . . . . . . 33 3.8.5. Locator Options . . . . . . . . . . . . . . . . . . . 34
3.9.1. Format of Objective Options . . . . . . . . . . . . . 33 3.9. Objective Options . . . . . . . . . . . . . . . . . . . . 36
3.9.2. Objective flags . . . . . . . . . . . . . . . . . . . 34 3.9.1. Format of Objective Options . . . . . . . . . . . . . 36
3.9.3. General Considerations for Objective Options . . . . 35 3.9.2. Objective flags . . . . . . . . . . . . . . . . . . . 37
3.9.4. Organizing of Objective Options . . . . . . . . . . . 35 3.9.3. General Considerations for Objective Options . . . . 37
3.9.5. Experimental and Example Objective Options . . . . . 37 3.9.4. Organizing of Objective Options . . . . . . . . . . . 38
4. Implementation Status [RFC Editor: please remove] . . . . . . 37 3.9.5. Experimental and Example Objective Options . . . . . 39
4.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 37 4. Implementation Status [RFC Editor: please remove] . . . . . . 40
4.2. Python Implementation . . . . . . . . . . . . . . . . . . 38 4.1. BUPT C++ Implementation . . . . . . . . . . . . . . . . . 40
5. Security Considerations . . . . . . . . . . . . . . . . . . . 38 4.2. Python Implementation . . . . . . . . . . . . . . . . . . 40
6. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 40 5. Security Considerations . . . . . . . . . . . . . . . . . . . 41
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 6. CDDL Specification of GRASP . . . . . . . . . . . . . . . . . 43
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 44 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 45
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 44 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 47
9.1. Normative References . . . . . . . . . . . . . . . . . . 44 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 47
9.2. Informative References . . . . . . . . . . . . . . . . . 45 9.1. Normative References . . . . . . . . . . . . . . . . . . 47
Appendix A. Open Issues . . . . . . . . . . . . . . . . . . . . 48 9.2. Informative References . . . . . . . . . . . . . . . . . 48
Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 49 Appendix A. Open Issues . . . . . . . . . . . . . . . . . . . . 51
Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 55 Appendix B. Closed Issues [RFC Editor: Please remove] . . . . . 52
Appendix D. Capability Analysis of Current Protocols . . . . . . 59 Appendix C. Change log [RFC Editor: Please remove] . . . . . . . 59
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 62 Appendix D. Capability Analysis of Current Protocols . . . . . . 63
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 66
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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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
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 instance of GRASP will exist o It is normally expected that a single main instance of GRASP will
in an autonomic node, and that the protocol engine and each ASA exist in an autonomic node, and that the protocol engine and each
will run as independent asynchronous processes. ASA will run as independent asynchronous processes. However,
separate GRASP instances may exist for security reasons
(Section 3.3.2).
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 3.3.3. For some objectives, especially those concerned Section 3.3.4. 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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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
Key Infrastructure (PKI) [RFC5280] managed within the autonomic Key Infrastructure (PKI) [RFC5280] managed within the autonomic
network itself. The details of such a PKI and how its boundary is network itself. The details of such a PKI and how its boundary is
established are out of scope for this document. DTLS [RFC6347] MAY established are out of scope for this document. DTLS [RFC6347] MAY
be used but since GRASP operations usually involve several messages be used but since GRASP operations usually involve several messages
this is not expected to be advantageous. this is not expected to be advantageous.
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 any GRASP functions except discovery if there is refuse to execute GRASP synchronization and negotiation functions if
neither an operational ACP nor an operational TLS environment. there is neither an operational ACP nor an operational TLS or DTLS
environment.
As mentioned in Section 3.2, limited GRASP operations might be Link-local multicast is used for discovery messages. Responses to
discovery messages MUST be secured, with one exception mentioned in
the next section.
3.3.2. Limited Security Instances
This section describes three cases where additional instances of
GRASP are appropriate.
1) As mentioned in Section 3.2, 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 authenticated and SHOULD be agreement. Such operations MUST be confined to a separate instance
encrypted. TLS is RECOMMENDED for this purpose. of GRASP with its own copy of all GRASP data structures. Messages
MUST be authenticated and SHOULD be encrypted. TLS is RECOMMENDED
for this purpose.
Link-local multicast is used for discovery messages. Responses to 2) During initialisation, before a node has joined the applicable
discovery messages MUST be secured, with one exception. trust infrastructure, [I-D.ietf-anima-bootstrapping-keyinfra], it is
impossible to secure messages. Thus, the security bootstrap process
needs to use insecure GRASP discovery, response and flood messages.
Such usage MUST be limited to link-local operations and MUST be
confined to a separate insecure instance of GRASP with its own copy
of all GRASP data structures. This instance is nicknamed DULL -
Discovery Unsolicited Link Local.
The exception is that during initialisation, before a node has joined The detailed rules for the DULL instance of GRASP are as follows:
the applicable trust infrastructure, e.g.,
[I-D.ietf-anima-bootstrapping-keyinfra], or before the ACP is fully
established, it might be impossible to secure messages. Indeed, both
the security bootstrap process and the ACP creation process might use
insecure GRASP discovery and response messages. Such usage MUST be
limited to the strictly necessary minimum. A full analysis of the
initialisation process is out of scope for the present document.
3.3.2. Transport Layer Usage o An initiator MUST only send Discovery or Flood Synchronization
link-local multicast messages with a loop count of 1. A responder
MAY send a Discovery Response message. Other GRASP message types
MUST NOT be sent.
o A responder MUST silently discard any message whose loop count is
not 1.
o A responder MUST silently discard any message referring to a GRASP
Objective that is not directly part of the bootstrap creation
process.
o A responder MUST NOT relay any multicast messages.
o A Discovery Response MUST indicate a link-local address.
o A Discovery Response MUST NOT include a Divert option.
o A node MUST silently discard any message whose source address is
not link-local.
3) During ACP formation [I-D.ietf-anima-autonomic-control-plane], a
separate instance of GRASP is used, with unicast messages secured by
TLS, and with its own copy of all GRASP data structures. This
instance is nicknamed SONN - Secure Only Neighbor Negotiation.
The detailed rules for the SONN instance of GRASP are as follows:
o Any type of GRASP message MAY be sent.
o An initiator MUST send any Discovery or Flood Synchronization
link-local multicast messages with a loop count of 1.
o A responder MUST silently discard any Discovery or Flood
Synchronization message whose loop count is not 1.
o A responder MUST silently discard any message referring to a GRASP
Objective that is not directly part of the ACP creation process.
o A responder MUST NOT relay any multicast messages.
o A Discovery Response MUST indicate a link-local address.
o A Discovery Response MUST NOT include a Divert option.
o A node MUST silently discard any message whose source address is
not link-local.
3.3.3. 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
itself does not provide for error detection or retransmission. Use itself does not provide for error detection or retransmission. Use
of an unreliable transport protocol is therefore NOT RECOMMENDED. of an unreliable transport protocol is therefore NOT RECOMMENDED.
When running within a secure ACP on reliable infrastructure, UDP MAY Nevertheless, when running within a secure ACP on reliable
be used for unicast messages not exceeding the minimum IPv6 path MTU; infrastructure, UDP MAY be used for unicast messages not exceeding
however, TCP MUST be used for longer messages. In other words, IPv6 the minimum IPv6 path MTU; however, TCP MUST be used for longer
fragmentation is avoided. If a node receives a UDP message but the messages. In other words, IPv6 fragmentation is avoided. If a node
reply is too long, it MUST open a TCP connection to the peer for the receives a UDP message but the reply is too long, it MUST open a TCP
reply. Note that when the network is under heavy load or in a fault connection to the peer for the reply. Note that when the network is
condition, UDP might become unreliable. Since this is when autonomic under heavy load or in a fault condition, UDP might become
functions are most necessary, automatic fallback to TCP MUST be unreliable. Since this is when autonomic functions are most
implemented. The simplest implementation is therefore to use only necessary, automatic fallback to TCP MUST be implemented. The
TCP. simplest implementation is therefore to use only TCP. In particular,
to guarantee interoperability during bootstrap and startup, using TCP
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. document. Transport protocols other than TCP and UDP are also out of
scope for this document.
For link-local multicast, the GRASP protocol listens to the GRASP For link-local multicast, the GRASP protocol listens to the well-
Listen Port (Section 3.5). This port is also used to listen for known GRASP Listen Port (Section 3.5). For unicast transport
unicast discovery responses. For unicast transport sessions used for sessions used for discovery responses, synchronization and
synchronization and negotiation, the ASA concerned listens on its own negotiation, the ASA concerned normally listens on its own
dynamically assigned port, which is communicated to its peers during dynamically assigned ports, which are communicated to its peers
discovery. during discovery. However, a minimal implementation MAY use the
GRASP Listen Port for this purpose.
3.3.3. Discovery Mechanism and Procedures 3.3.4. Discovery Mechanism and Procedures
o Separated discovery and negotiation mechanisms o Separated discovery and negotiation mechanisms
Although discovery and negotiation or synchronization are Although discovery and negotiation or synchronization are
defined together in the GRASP, they are separated mechanisms. defined together in the GRASP, they are separated mechanisms.
The discovery process could run independently from the The discovery process could run independently from the
negotiation or synchronization process. Upon receiving a negotiation or synchronization process. Upon receiving a
Discovery (Section 3.7.3) message, the recipient node should Discovery (Section 3.7.3) message, the recipient node should
return a response message in which it either indicates itself return a response message in which it either indicates itself
as a discovery responder or diverts the initiator towards as a discovery responder or diverts the initiator towards
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After a GRASP device successfully discovers a locator for a After a GRASP device successfully discovers a locator for a
Discovery Responder supporting a specific objective, it MUST Discovery Responder supporting a specific objective, it MUST
cache this information, including the interface identifier via cache this information, including the interface identifier via
which it was discovered. This cache record MAY be used for which it was discovered. This cache record MAY be used for
future negotiation or synchronization, and the locator SHOULD future negotiation or synchronization, and the locator SHOULD
be passed on when appropriate as a Divert option to another be passed on when appropriate as a Divert option to another
Discovery Initiator. Discovery Initiator.
The cache mechanism MUST include a lifetime for each entry. The cache mechanism MUST include a lifetime for each entry.
The lifetime is an implementation choice that MAY be modified The lifetime is derived from a time-to-live (ttl) parameter in
by network Intent. In some environments, unplanned address each Discovery Response message. Cached entries MUST be
renumbering might occur. In such cases, the cache lifetime ignored or deleted after their lifetime expires. In some
SHOULD be short compared to the typical address lifetime and a environments, unplanned address renumbering might occur. In
mechanism to flush the discovery cache SHOULD be implemented. such cases, the lifetime SHOULD be short compared to the
The discovery mechanism needs to track the node's current typical address lifetime and a mechanism to flush the discovery
address to ensure that Discovery Responses always indicate the cache SHOULD be implemented. The discovery mechanism needs to
correct address. 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 multiple Discovery Responders are found for the same
objective, they SHOULD all be cached, unless this creates a objective, they SHOULD all be cached, unless this creates a
resource shortage. The method of choosing between multiple resource shortage. The method of choosing between multiple
responders is an implementation choice. This choice MUST be responders is an implementation choice. This choice MUST be
available to each ASA but the GRASP implementation SHOULD available to each ASA but the GRASP implementation SHOULD
provide a default choice. provide a default choice.
Because Discovery Responders will be cached in a finite cache, Because Discovery Responders will be cached in a finite cache,
they might be deleted at any time. In this case, discovery they might be deleted at any time. In this case, discovery
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receiving the relayed discovery supports the discovery objective, receiving the relayed discovery supports the discovery objective,
it will respond to the relayed discovery. If it has a cached it will respond to the relayed discovery. If it has a cached
response, it will respond with that. If not, it will repeat the response, it will respond with that. If not, it will repeat the
discovery process, which thereby becomes recursive. The loop discovery process, which thereby becomes recursive. The loop
count and timeout will ensure that the process ends. count and timeout will ensure that the process ends.
o Rapid Mode (Discovery/Negotiation binding) o Rapid Mode (Discovery/Negotiation binding)
A Discovery message MAY include a Negotiation Objective option. A Discovery message MAY include a Negotiation Objective option.
This allows a rapid mode of negotiation described in This allows a rapid mode of negotiation described in
Section 3.3.4. A similar mechanism is defined for Section 3.3.5. A similar mechanism is defined for
synchronization in Section 3.3.5. synchronization in Section 3.3.6.
3.3.4. Negotiation Procedures 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.
3.3.5. 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
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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 3.7.8).
3.3.4.1. Rapid Mode (Discovery/Negotiation Linkage) 3.3.5.1. 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
that does not support rapid mode, before such a Negotiation 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 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.
3.3.5. Synchronization and Flooding Procedure 3.3.6. 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 3.7.9)
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 3.5), 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 3.6). An exponential backoff SHOULD be used for
subsequent repetitions. subsequent repetitions.
3.3.5.1. Flooding 3.3.6.1. 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 3.5).
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the result is zero. Also, it MUST limit the total rate at which it the result is zero. Also, it MUST limit the total rate at which it
relays Flood Synchronization messages to a reasonable value, in order relays Flood Synchronization messages to a reasonable value, in order
to mitigate possible denial of service attacks. It MUST cache the to mitigate possible denial of service attacks. It MUST cache the
Session ID value and initiator address of each relayed Flood Session ID value and initiator address of each relayed Flood
Synchronization message for a finite time not less than twice Synchronization message for a finite time not less than twice
GRASP_DEF_TIMEOUT milliseconds. To prevent loops, it MUST NOT relay GRASP_DEF_TIMEOUT milliseconds. To prevent loops, it MUST NOT relay
a Flood Synchronization message which carries a given cached Session a Flood Synchronization message which carries a given cached Session
ID and initiator address more than once. These precautions avoid ID and initiator address more than once. These precautions avoid
synchronization loops and mitigate potential overload. synchronization loops and mitigate potential overload.
Note that this mechanism is unreliable in the case of sleeping nodes. Note that this mechanism is unreliable in the case of sleeping nodes,
Sleeping nodes that require an objective subject to flooding SHOULD or new nodes that join the network, or nodes that rejoin the network
periodically request unicast synchronization for that objective. after a fault. An ASA that initiates a flood SHOULD repeat the flood
at a suitable frequency and SHOULD also act as a synchronization
responder for the objective(s) concerned. Thus nodes that require an
objective subject to flooding can either wait for the next flood or
request unicast synchronization for that objective.
The multicast messages for synchronization flooding are subject to The multicast messages for synchronization flooding are subject to
the security rules in Section 3.3.1. In practice this means that the security rules in Section 3.3.1. 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.
3.3.5.2. Rapid Mode (Discovery/Synchronization Linkage) 3.3.6.2. 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 3.7.9 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
that does not support rapid mode, before such a Synchronization
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 3.4. High Level Deployment Model
It is expected that a GRASP implementation will reside in an It is expected that a GRASP implementation will reside in an
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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 UDP and TCP port that every GRASP-enabled network device always A well-known UDP user port that every GRASP-enabled network device
listens to. MUST always listen to for link-local multicasts. Additionally,
this user port MAY be used to listen for TCP or UDP unicast
messages in a simple implementation of GRASP (Section 3.3.3).
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.
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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 3.7.4. 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, response-message = [M_RESPONSE, session-id, initiator, ttl,
(+locator-option // divert-option), ?objective)] (+locator-option // divert-option), ?objective)]
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. It Response message if and only if it can respond to the discovery.
MUST contain the same Session ID and initiator as the Discovery
message. It MAY include a copy of the discovery objective from the It MUST contain the same Session ID and initiator as the Discovery
Discovery message. It is sent to the sender of the Discovery message message.
via TCP at the port GRASP_LISTEN_PORT.
It MUST contain a time-to-live (ttl) for the validity of the
response, given as a positive integer value in milliseconds. Zero
is treated as the default value GRASP_DEF_TIMEOUT (Section 3.5).
It MAY include a copy of the discovery objective from the
Discovery message.
It is sent to the sender of the Discovery message via TCP at the port
used to send the Discovery message.
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 3.8.5) 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 3.8.2) 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
Section 3.3.4.
3.7.5. Request Messages 3.7.5. 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
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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 3.7.10. 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, +objective] flood-message = [M_FLOOD, session-id, initiator, ttl,
(locator-option / []), +objective]
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 3.3.5. The initiator address is provided with the rules in Section 3.3.6.
as described for Discovery messages. The synchronization data will
be in the form of GRASP Option(s) for specific synchronization
objective(s). The loop count(s) MUST be set to a suitable value to
prevent flood loops (default value is GRASP_DEF_LOOPCT).
A node that receives a Flood Synchronization message SHOULD cache the The initiator address is provided as described for Discovery
received objectives for use by local ASAs. messages.
The message MUST contain a time-to-live (ttl) for the validity of
the response, given as a positive integer value in milliseconds.
There is no default; zero indicates an indefinite lifetime.
The message MAY contain a locator option indicating the ASA that
initiated the flooded data. In its absence, an empty option MUST
be included.
The synchronization data are in the form of GRASP Option(s) for
specific synchronization objective(s). The loop count(s) MUST be
set to a suitable value to prevent flood loops (default value is
GRASP_DEF_LOOPCT).
A node that receives a Flood Synchronization message MUST cache the
received objectives for use by local ASAs. Each cached objective
MUST be tagged with the locator option sent with it, or with a null
tag if an empty locator option was sent. If a subsequent Flood
Synchronization message carrying the same objective arrives with the
same tag, the corresponding cached copy of the objective MUST be
overwritten. If a subsequent Flood Synchronization message carrying
the same objective arrives with a different tag, a new cached entry
MUST be created.
Note: the purpose of this mechanism is to allow the recipient of
flooded values to distinguish between different senders of the same
objective, and if necessary communicate with them using the locator,
protocol and port included in the locator option. Many objectives
will not need this mechanism, so they will be flooded with a null
locator.
Cached entries MUST be ignored or deleted after their lifetime
expires.
3.7.11. No Operation Message 3.7.11. 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.
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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 3.7.6. It is also used for terminating
discovery as described in Section 3.3.3, and for terminating flooding discovery as described in Section 3.3.4, and for terminating flooding
as described in Section 3.3.5.1. as described in Section 3.3.6.1.
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 3.9.2. Objective flags
An objective may be relevant for discovery only, for discovery and An objective may be relevant for discovery only, for discovery and
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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. Debian.
o Coverage: Corresponds to draft-ietf-anima-grasp-05. Limitations o Coverage: Corresponds to draft-ietf-anima-grasp-07. 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
* relay code is lazy (no rate control) * relay code is lazy (no rate control)
* all unicast transactions use TCP (no unicast UDP) * all unicast transactions use TCP (no unicast UDP).
Experimental code for unicast UDP proved to be complex and
brittle.
* optional Objective option in Response messages not implemented * optional Objective option in Response messages not implemented
* workarounds for defects in Python socket module and Windows * workarounds for defects in Python socket module and Windows
socket peculiarities socket peculiarities
o Licensing: Simplified BSD o Licensing: Simplified BSD
o Experience: https://www.cs.auckland.ac.nz/~brian/graspy/graspy.pdf o Experience: https://www.cs.auckland.ac.nz/~brian/graspy/graspy.pdf
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mechanism, for example during system bootstrap (Section 3.3.1), mechanism, for example during system bootstrap (Section 3.3.1),
the Session ID (Section 3.6) will act as a nonce to provide the Session ID (Section 3.6) 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. It SHOULD apply obvious precautions such as allowing support. An implementation might support precautions such as
only one ASA in a given node to modify a given objective, but allowing only one ASA in a given node to modify a given objective,
otherwise authorization is out of scope. but this may not be appropriate in all cases. For example, it
might be operationally useful to allow an old and a new version of
the same ASA to run simultaneously during an overlap period.
These questions are out of scope for the present specification.
- Privacy and confidentiality - Privacy and confidentiality
Generally speaking, no personal information is expected to be Generally speaking, no personal information is expected to be
involved in the signaling protocol, so there should be no direct involved in the signaling protocol, so there should be no direct
impact on personal privacy. Nevertheless, traffic flow paths, impact on personal privacy. Nevertheless, traffic flow paths,
VPNs, etc. could be negotiated, which could be of interest for VPNs, etc. could be negotiated, which could be of interest for
traffic analysis. Also, operators generally want to conceal traffic analysis. Also, operators generally want to conceal
details of their network topology and traffic density from details of their network topology and traffic density from
outsiders. Therefore, since insider attacks cannot be excluded in outsiders. Therefore, since insider attacks cannot be excluded in
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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 3.3.1), 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 3.3.5.1. messages are suggested in Section 3.3.6.1.
- 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. Relevant mitigations are specified in
Section 3.3.3. Additionally, it is of great importance that Section 3.3.4. Additionally, it is of great importance that
firewalls prevent any GRASP messages from entering the domain from firewalls prevent any GRASP messages from entering the domain from
an untrusted source. 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. will be impossible until enrollment is complete. Further details
are given in Section 3.3.2.
- 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 3.3.1). 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
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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..16777215 ;up to 24 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, response-message = [M_RESPONSE, session-id, initiator, ttl,
(+locator-option // divert-option), ?objective] (+locator-option // divert-option), ?objective]
message /= synch-message ;response to Synchronization request message /= synch-message ;response to Synchronization request
synch-message = [M_SYNCH, session-id, objective] synch-message = [M_SYNCH, session-id, objective]
message /= flood-message message /= flood-message
flood-message = [M_FLOOD, session-id, initiator, +objective] flood-message = [M_FLOOD, session-id, initiator, ttl,
(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]
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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
ttl = 0..4294967295 ; in milliseconds
locator-option /= [O_IPv4_LOCATOR, ipv4-address, 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
locator-option /= [O_IPv6_LOCATOR, ipv6-address, 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
locator-option /= [O_FQDN_LOCATOR, text, transport-proto, port-number] locator-option /= [O_FQDN_LOCATOR, text, transport-proto, port-number]
skipping to change at page 42, line 48 skipping to change at page 45, line 49
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 General Discovery and Negotiation Protocol This document defines the Generic Autonomic Signaling Protocol
(GRASP). (GRASP).
Section 3.5 explains the following link-local multicast addresses, Section 3.5 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 UDP and TCP port, which IANA is Section 3.5 explains the following User Port, which IANA is requested
requested to assign for use by GRASP: 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)
Transport Protocols: UDP, TCP
Assignee: iesg@ietf.org
Contact: chair@ietf.org
Description: See Section 3.5
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 45, line 39 skipping to change at page 48, line 44
9.2. Informative References 9.2. Informative References
[I-D.chaparadza-intarea-igcp] [I-D.chaparadza-intarea-igcp]
Behringer, M., Chaparadza, R., Petre, R., Li, X., and H. Behringer, M., Chaparadza, R., Petre, R., Li, X., and H.
Mahkonen, "IP based Generic Control Protocol (IGCP)", Mahkonen, "IP based Generic Control Protocol (IGCP)",
draft-chaparadza-intarea-igcp-00 (work in progress), July draft-chaparadza-intarea-igcp-00 (work in progress), July
2011. 2011.
[I-D.ietf-anima-autonomic-control-plane] [I-D.ietf-anima-autonomic-control-plane]
Behringer, M., Bjarnason, S., BL, B., and T. Eckert, "An Behringer, M., Eckert, T., and S. Bjarnason, "An Autonomic
Autonomic Control Plane", draft-ietf-anima-autonomic- Control Plane", draft-ietf-anima-autonomic-control-
control-plane-02 (work in progress), March 2016. plane-03 (work in progress), July 2016.
[I-D.ietf-anima-bootstrapping-keyinfra] [I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Behringer, M., and S. Pritikin, M., Richardson, M., Behringer, M., and S.
Bjarnason, "Bootstrapping Key Infrastructures", draft- Bjarnason, "Bootstrapping Remote Secure Key
ietf-anima-bootstrapping-keyinfra-02 (work in progress), Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
March 2016. keyinfra-03 (work in progress), June 2016.
[I-D.ietf-anima-reference-model] [I-D.ietf-anima-reference-model]
Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L., Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
Liu, B., Nobre, J., and J. Strassner, "A Reference Model Pierre, P., Liu, B., Nobre, J., and J. Strassner, "A
for Autonomic Networking", draft-ietf-anima-reference- Reference Model for Autonomic Networking", draft-ietf-
model-01 (work in progress), March 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-00 (work in progress), January 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-13 (work in Protocol", draft-ietf-netconf-restconf-16 (work in
progress), April 2016. progress), August 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.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
skipping to change at page 48, line 49 skipping to change at page 52, line 5
[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
o 7. Cross-check against other ANIMA WG documents for consistency o 7. Cross-check against other ANIMA WG documents for consistency
and gaps. and gaps.
o 43. Rapid mode synchronization and negotiation is currently
limited to a single objective for simplicity of design and
implementation. A future consideration is to allow multiple
objectives in rapid mode for greater efficiency.
o 48. Should the Appendix "Capability Analysis of Current
Protocols" be deleted before RFC publication?
o 49. Section 3.3.1 should say more about signaling between two
autonomic networks/domains.
o 50. Is Rapid mode limited to on-link only? What happens if first
discovery responder does not support Rapid Mode? (Section 3.3.4,
Section 3.3.5)
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
exceed a reasonable MTU, a TCP mode will be required in any case. exceed a reasonable MTU, a TCP mode will be required in any case.
skipping to change at page 53, line 15 skipping to change at page 55, line 51
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 3.3.5.1). o 27. Security of Flood multicasts (Section 3.3.6.1).
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.
skipping to change at page 55, line 5 skipping to change at page 57, line 40
RESOLVED: Both would be possible, but (b) is preferred. RESOLVED: Both would be possible, but (b) is preferred.
o 42. Do we need a feature whereby an ASA can bypass the ACP and o 42. Do we need a feature whereby an ASA can bypass the ACP and
use the data plane for efficiency/throughput? This would require use the data plane for efficiency/throughput? This would require
discovery to return non-ACP addresses and would evade ACP discovery to return non-ACP addresses and would evade ACP
security. security.
RESOLVED: This is considered out of scope for GRASP, but a comment RESOLVED: This is considered out of scope for GRASP, but a comment
has been added in security considerations. has been added in security considerations.
o 43. Rapid mode synchronization and negotiation is currently
limited to a single objective for simplicity of design and
implementation. A future consideration is to allow multiple
objectives in rapid mode for greater efficiency.
RESOLVED: This is considered out of scope for this version.
o 44. In requirement T9, the words that encryption "may not be o 44. In requirement T9, the words that encryption "may not be
required in all deployments" were removed. Is that OK?. required in all deployments" were removed. Is that OK?.
RESOLVED: No objections. RESOLVED: No objections.
o 45. Device Identity Option is unused. Can we remove it o 45. Device Identity Option is unused. Can we remove it
completely?. completely?.
RESOLVED: No objections. Done. RESOLVED: No objections. Done.
skipping to change at page 55, line 32 skipping to change at page 58, line 27
RESOLVED: Yes. Done. RESOLVED: Yes. Done.
o 47. REQUEST is a dual purpose message (request negotiation or o 47. REQUEST is a dual purpose message (request negotiation or
request synchronization). Would it be better to split this into request synchronization). Would it be better to split this into
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
Protocols" be deleted before RFC publication?
RESOLVED: No (per WG meeting at IETF 96).
o 49. Section 3.3.1 Should say more about signaling between two
autonomic networks/domains.
RESOLVED: Description of separate GRASP instance added.
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,
Section 3.3.6)
RESOLVED: Not limited to on-link. First responder wins.
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
cache with their source locator?
RESOLVED: TTL added to Flood (and Discovery Response) messages.
Cached flooded objectives must be tagged with their originating
ASA locator, and multiple copies must be kept if necessary.
o 52. Describe in detail what is allowed and disallowed in an
insecure instance of GRASP.
RESOLVED: Done.
o 53. Tune IANA Considerations to support early assignment request.
RESOLVED: Done.
Appendix C. Change log [RFC Editor: Please remove] Appendix C. Change log [RFC Editor: Please remove]
draft-ietf-anima-grasp-07, 2016-09-13:
Protocol change: Added TTL field to Flood message (issue 51).
Protocol change: Added Locator option to Flood message (issue 51).
Protocol change: Added TTL field to Discovery Response message
(corrollary to issue 51).
Clarified details of rapid mode (issues 43 and 50).
Description of inter-domain GRASP instance added (issue 49).
Description of limited security GRASP instances added (issue 52).
Strengthened advice to use TCP rather than UDP.
Updated IANA considerations and text about well-known port usage
(issue 53).
Amended text about ASA authorization and roles to allow for
overlapping ASAs.
Added text recommending that Flood should be repeated periodically.
Editorial fixes.
draft-ietf-anima-grasp-06, 2016-06-27: draft-ietf-anima-grasp-06, 2016-06-27:
Added text on discovery cache timeouts. Added text on discovery cache timeouts.
Noted that ASAs that are only initiators do not need to respond to Noted that ASAs that are only initiators do not need to respond to
discovery message. discovery message.
Added text on unexpected address changes. Added text on unexpected address changes.
Added text on robust implementation. Added text on robust implementation.
skipping to change at page 59, line 36 skipping to change at page 63, line 43
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. Capability Analysis of Current Protocols
This appendix discusses various existing protocols with properties This appendix discusses various existing protocols with properties
related to the above negotiation and synchronisation requirements. related to the requirements described in Section 2. The purpose is
The purpose is to evaluate whether any existing protocol, or a simple to evaluate whether any existing protocol, or a simple combination of
combination of existing protocols, can meet those requirements. existing protocols, can meet those requirements.
Numerous protocols include some form of discovery, but these all Numerous protocols include some form of discovery, but these all
appear to be very specific in their applicability. Service Location appear to be very specific in their applicability. Service Location
Protocol (SLP) [RFC2608] provides service discovery for managed Protocol (SLP) [RFC2608] provides service discovery for managed
networks, but requires configuration of its own servers. DNS-SD networks, but requires configuration of its own servers. DNS-SD
[RFC6763] combined with mDNS [RFC6762] provides service discovery for [RFC6763] combined with mDNS [RFC6762] provides service discovery for
small networks with a single link layer. [RFC7558] aims to extend small networks with a single link layer. [RFC7558] aims to extend
this to larger autonomous networks but this is not yet standardized. this to larger autonomous networks but this is not yet standardized.
However, both SLP and DNS-SD appear to target primarily application However, both SLP and DNS-SD appear to target primarily application
layer services, not the layer 2 and 3 objectives relevant to basic layer services, not the layer 2 and 3 objectives relevant to basic
skipping to change at page 60, line 48 skipping to change at page 65, line 4
GIST as a synchronization and negotiation protocol. They do not GIST as a synchronization and negotiation protocol. They do not
appear to be directly useable for peer discovery. appear to be directly useable for peer discovery.
We now consider two protocols that are works in progress at the time We now consider two protocols that are works in progress at the time
of this writing. Firstly, RESTCONF [I-D.ietf-netconf-restconf] is a of this writing. Firstly, RESTCONF [I-D.ietf-netconf-restconf] is a
protocol intended to convey NETCONF information expressed in the YANG protocol intended to convey NETCONF information expressed in the YANG
language via HTTP, including the ability to transit HTML language via HTTP, including the ability to transit HTML
intermediaries. While this is a powerful approach in the context of intermediaries. While this is a powerful approach in the context of
centralised configuration of a complex network, it is not well centralised configuration of a complex network, it is not well
adapted to efficient interactive negotiation between peer devices, adapted to efficient interactive negotiation between peer devices,
especially simple ones that are unlikely to include YANG processing especially simple ones that might not include YANG processing
already. already.
Secondly, we consider Distributed Node Consensus Protocol (DNCP) Secondly, we consider Distributed Node Consensus Protocol (DNCP)
[RFC7787]. This is defined as a generic form of state [RFC7787]. This is defined as a generic form of state
synchronization protocol, with a proposed usage profile being the synchronization protocol, with a proposed usage profile being the
Home Networking Control Protocol (HNCP) [RFC7788] for configuring Home Networking Control Protocol (HNCP) [RFC7788] for configuring
Homenet routers. A specific application of DNCP for autonomic Homenet routers. A specific application of DNCP for autonomic
networking was proposed in [I-D.stenberg-anima-adncp]. networking was proposed in [I-D.stenberg-anima-adncp].
DNCP "is designed to provide a way for each participating node to DNCP "is designed to provide a way for each participating node to
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