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Versions: (draft-ali-ccamp-rsvp-node-id-based-hello)
00 01 02 03 RFC 4558
Network Working Group Zafar Ali
Internet Draft Reshad Rahman
Category: Proposed Standard Danny Prairie
Expires: September 2006 Cisco Systems
D. Papadimitriou
Alcatel
March 2006
Node ID based RSVP Hello: A Clarification Statement
draft-ietf-ccamp-rsvp-node-id-based-hello-03.txt
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Copyright Notice
Copyright (C) The Internet Society (2006). All Rights Reserved.
Abstract
Use of Node-ID based RSVP Hello messages is implied in a number of
cases, e.g., when data and control plan are separated, and when TE links
are unnumbered. Nonetheless, this implied behavior is unclear
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and this document formalizes use of Node-ID based RSVP Hello session
in some scenarios. The procedure described in this document applies
to both Multi-Protocol Label Switching (MPLS) and Generalized MPLS
(GMPLS) capable nodes.
When link level failure detection is performed by some means other
than exchanging RSVP Hello messages, use of Node-ID based Hello
session is optimal for detecting signaling adjacency failure for
Resource reSerVation Protocol-Traffic Engineering (RSVP-TE). The use
of Node-ID based Hello session is optimal in the sense that as long as
there is IP reachability to the nieghbor (node-id), the signalling
adjacency will remain up.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1. Terminology
Node-ID: TE Router ID as advertised in the Router Address TLV for
OSPF [OSPF-TE] and Traffic Engineering Router ID TLV for ISIS [ISIS-
TE]. For IPv6, the Node-ID refers to the Router_IPv6_Address for
OSPFv3 [OSPFv3-TE] and the IPv6 TE Router_ID for IS-IS [IS-ISv6-TE].
Node-ID based Hello Session: A Hello session such that local and
remote Node-IDs are used in the source and destination fields of the
Hello packet, respectively.
Interface bounded Hello Session: A Hello session such that local and
remote addresses of the interface in question are used in the source
and destination fields of the Hello packet, respectively.
2. Introduction
The RSVP Hello message exchange was introduced in [RFC 3209]. The
usage of RSVP Hello has been extended in [RFC 3473] to support RSVP
Graceful Restart (GR) procedures.
More specifically, [RFC 3473] specifies the use of the RSVP Hello
messages for GR procedures for Generalized MPLS (GMPLS). GMPLS
introduces the notion of control plane and data plane separation. In
other words, in GMPLS networks, the control plane information is
carried over a control network whose end-points are IP capable, and
which may be physically or logically disjoint from the data bearer
links it controls. One of the consequences of separation of data
bearer links from control channels is that RSVP Hello messages are
not terminated on data bearer links' interfaces even if (some of)
those are numbered. Instead RSVP Hello messages are terminated at the
control channel (IP-capable) end-points. The latter MAY be identified
by the value assigned to the node hosting these control channels i.e.
Node-ID. Consequently, the use of RSVP Hello messages for GR
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applications introduces a need for clarifying the behavior and usage
of Node-ID based Hello sessions.
Even in the case of packet switching capable end-points, when link
failure detection is performed by some means other than RSVP Hello
messages (e.g., [BFD]), the use of Node-ID based Hello sessions is
also optimal for detection of signaling adjacency failures for GMPLS-
/RSVP-TE when there is more than one link between a pair of nodes.
Similarly, when all TE links between neighbor nodes are unnumbered,
it is implied that the nodes will exchange Node-ID based Hello
messages for detection of signaling adjacency failures. This document
also clarifies the use of Node-ID based Hello message exchanges when
all or a sub-set of TE links are unnumbered.
3. Node-ID based RSVP Hello Messages
A Node-ID based Hello session is established through the exchange of
RSVP Hello messages such that local and remote Node-IDs are
respectively used in the source and destination fields of Hello
packets. Here, Node-ID refers for IPv4 to the TE router-id as defined
in the Router Address TLV for OSPF [OSPF-TE] and the Traffic
Engineering router ID TLV for ISIS [ISIS-TE]. For IPv6, the Node-ID
refers to the Router_IPv6_Address for OSPFv3 [OSPFv3-TE] and the IPv6
TE Router_ID for IS-IS [IS-ISv6-TE]. This section formalizes a
procedure for establishing Node-ID based Hello sessions.
If a node wishes to establish a Node-ID based RSVP Hello session with
its neighbor, it sends a Hello message with its Node-ID in the source
IP address field of the Hello packet. Furthermore, the node also puts
the neighbor's Node-ID in the destination address field of the IP
packet.
When a node receives a Hello packet where the destination IP address
is its local Node-ID as advertised in the IGP-TE topology, the node
MUST use its Node-ID in replying to the Hello message. In other
words, nodes MUST ensure that the Node-IDs used in RSVP Hello
messages are those derived/contained in the IGP-TE topology.
Furthermore, a node can only run one Node-ID based RSVP Hello session
per IGP instance (i.e., per Node-ID pair) with its neighbor.
Even in the case of packet switching capable end-points, when link
failure detection is performed by some means other than exchanging
RSVP Hello messages, use of Node-ID based Hello sessions is also
optimal in detecting signaling adjacency failures for GMPLS-/RSVP-TE
when there is more than one link between a pair of nodes. Similarly,
if all interfaces between a pair of nodes are unnumbered, the optimal
way to use RSVP to detect signaling adjacency failure is to run Node-
ID based Hello sessions. Furthermore, in the case of optical network
with single or multiple, numbered or unnumbered control channels, use
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of Node-ID based Hello messages for detecting signaling adjacency
failure is also optimal. Therefore, when link failure detection is
performed by some means other than exchanging RSVP Hello messages, or
if all interfaces between a pair of nodes are unnumbered, or in GMPLS
network with data and control plane separation, a node MUST run Node-
ID based Hello sessions for detection of signaling adjacency failure
for RSVP-TE. Nonetheless, if it is desirable to distinguish between
signaling adjacency and link failures, Node-ID based Hello sessions
can co-exist with the exchange of interface bound Hellos messages.
Similarly, if a pair of nodes share numbered and unnumbered TE links,
Node-ID and interface based Hello sessions can co-exist.
4. Backward Compatibility Note
The procedure presented in this document is backward compatible with
both [RFC3209] and [RFC3473].
Per [RFC 3209], the Hello mechanism is intended for use between
immediate neighbors and Hello messages are by default sent between
direct RSVP neighbors. This document does not modify this behavior as
it uses as "local node_id" the IPv4/IPv6 source address of the
sending node and as "remote node_id" the IPv4/IPv6 destination
address of the neighbor node. TTL/Hop Limit setting and processing
are also left unchanged.
Moreover, this document does not modify the use of Hello Processing
for State Recovery as defined in Section 9.3 of [RFC 3473] (including
definition and processing of the RESTART_CAP object).
5. Security Considerations
As this document does not modify or extend the RSVP Hello messages
exchange between immediate RSVP neighbors, it does not introduce new
security considerations.
The security considerations pertaining to the original [RFC3209]
remain relevant. RSVP message security is described in [RFC2747] and
provides Hello message integrity and authentication of the Node-ID
ownership.
6. Acknowledgements
We would like to thank Anca Zamfir, Jean-Louis Le Roux, Arthi
Ayyangar and Carol Iturralde for their useful comments and
suggestions.
7. IANA Considerations
This draft makes no requests for IANA action.
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8. Reference
8.1 Normative Reference
[RFC2205] Braden, R., et al., "Resource ReSerVation Protocol (RSVP)
- Version 1, Functional Specification", RFC 2205,
September 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels," BCP 14, RFC 2119, March 1997.
[RFC2747] Baker, F., Lindell B., and Talwar, M., "RSVP
Cryptographic Authentication", RFC 2747, January 2000.
[RFC3209] Awduche, D., et al., "Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3471] Berger, L., et al., Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description, RFC
3471, January 2003.
[RFC3473] Berger, L., et al., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC
3473, January 2003.
[RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC
3667, February 2004.
[RFC3668] Bradner, S., Ed., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004.
8.2 Informative Reference
[OSPF-TE] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering
Extensions to OSPF Version 2", RFC 3630, September 2003.
[ISIS-TE] Li, T., Smit, H., "IS-IS extensions for Traffic
Engineering", RFC 3784, June 2004.
[BFD] Katz, D., and Ward, D., "Bidirectional Forwarding
Detection", draft-katz-ward-bfd, work in progress.
9. Author's Addresses
Zafar Ali
Cisco Systems Inc.
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100 South Main St. #200
Ann Arbor, MI 48104, USA.
Phone: (734) 276-2459
Email: zali@cisco.com
Reshad Rahman
Cisco Systems Inc.
2000 Innovation Dr.,
Kanata, Ontario, K2K 3E8, Canada.
Phone: (613)-254-3519
Email: rrahman@cisco.com
Danny Prairie
Cisco Systems Inc.
2000 Innovation Dr.,
Kanata, Ontario, K2K 3E8, Canada.
Phone: (613)-254-3519
Email: dprairie@cisco.com
Dimitri Papadimitriou (Alcatel)
Fr. Wellesplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 240-8491
Email: dimitri.papadimitriou@alcatel.be
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