CCAMP Working Group Zafar Ali
Reshad Rahman
Danny Prairie
Cisco Systems
D. Papadimitriou
Alcatel
Internet Draft
Category: BCP
Expires: October 2004 April 2004
Node ID based RSVP Hello: A Clarification Statement
draft-ali-ccamp-rsvp-node-id-based-hello-01.txt
Status of this Memo
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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, when TE links
are unnumbered. Furthermore, when link level failure detection is
performed by some means other than RSVP Hellos, use of node-id based
Hellos is optimal for detecting signaling adjacency failure for RSVP-
TE. Nonetheless, this implied behavior is unclear and this document
formalizes use of node-id based RSVP Hello sessions as a best current
practice (BCP) in some scenarios.
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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].
Routing Area ID Summary
(This section to be removed before publication.)
SUMMARY
This document clarifies use of node-id based RSVP Hellos.
WHERE DOES IT FIT IN THE PICTURE OF THE ROUTING AREA WORK?
This work fits in the context of [RFC 3209] and [RFC 3473].
WHY IS IT TARGETED AT THIS WG?
This document is targeted at ccamp as it clarifies procedures in
[RFC 3209] and [RFC 3473], related to use of RSVP-TE Hello protocol.
RELATED REFERENCES
Please refer to the reference section.
Table of Contents
1. Terminology....................................................2
2. Introduction...................................................3
3. Node-id based RSVP Hellos......................................3
4. Backward Compatibility Note....................................4
5. Security Considerations........................................4
6. Acknowledgements...............................................4
7. IANA Considerations............................................5
8. Reference......................................................5
8.1 Normative Reference........................................5
8.2 Informative Reference......................................5
9. Author's Addresses.............................................5
1. Terminology
Node-id: Router-id as advertised in the Router Address TLV for OSPF
[OSPF-TE] and Traffic Engineering router ID TLV for ISIS [ISIS-TE].
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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. Specifically, [RFC 3473] specifies
the use of the RSVP Hellos 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 Hellos are
not terminated on data bearer linksÆ interfaces even if (some of)
those are numbered. Instead RSVP hellos 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 Hellos for GR applications
introduces a need for clarifying the behavior and usage of node-id
based Hellos.
Even in the case of packet MPLS, when link failure detection is
performed by some means other than RSVP Hellos (e.g., [BFD]), the use
of node-id based Hellos is also optimal for detection of signaling
adjacency failures for RSVP-TE. Similarly, when all TE links between
neighbor nodes are unnumbered, it is implied that the nodes will use
node-id based Hellos for detection of signaling adjacency failures.
This document also clarifies the use of node-id based Hellos when all
or a sub-set of TE links are unnumbered. This draft also clarifies
use of node-id based Hellos in these scenarios.
3. Node-id based RSVP Hellos
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 to a router-id as defined in the Router
Address TLV for OSPF [OSPF-TE] and the Traffic Engineering router ID
TLV for ISIS [ISIS-TE]. This section formalizes a procedure for
establishing node-id based Hello sessions.
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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 neighborÆs 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.
In the case of packet MPLS, when link failure detection is performed
by some means other than RSVP Hellos, use of node-id based Hellos is
also optimal in detecting signaling adjacency failures, e.g., for
RSVP GR procedure. 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 Hellos. Furthermore, in the
case of optical network with single or multiple, numbered or
unnumbered control channels, use of node-id based Hellos for
detecting signaling adjacency failure is also optimal. Therefore,
when link failure detection is performed by some means other than
RSVP Hellos, 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 Hellos 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 Hellos can co-exist with interface bound
Hellos messages. Similarly, if a pair of nodes share numbered and
unnumbered TE links, node id and interface based Hellos can co-exist.
4. Backward Compatibility Note
The procedure presented in this document is backward compatible with
both [RFC3209] and [RFC3473].
5. Security Considerations
This document does not introduce new security issues. The security
considerations pertaining to the original [RFC3209] remain relevant.
6. Acknowledgements
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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
None.
8. Reference
8.1 Normative Reference
[RFC2205] "Resource ReSerVation Protocol (RSVP) - Version 1,
Functional Specification", RFC 2205, Braden, et al, September
1997.
[RFC3209] "Extensions to RSVP for LSP Tunnels", D. Awduche, et al,
RFC 3209, December 2001.
[RFC3471] Generalized Multi-Protocol Label Switching (GMPLS)
Signaling Functional Description, RFC 3471, L. Berger, et al,
January 2003.
[RFC3473] "Generalized Multi-Protocol Label Switching (GMPLS)
Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-
TE) Extensions", RFC 3473, L. Berger, et al, January 2003.
[RFC2119] "Key words for use in RFCs to Indicate Requirement Levels",
RFC 2119, S. Bradner, March 1997.
8.2 Informative Reference
[OSPF-TE] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering
Extensions to OSPF Version 2", RFC 3630.
[ISIS-TE] Li, T., Smit, H., "IS-IS extensions for Traffic
Engineering", draft-ietf-isis-traffic-05.txt (work in progress).
[BFD] Katz, D., and Ward, D., "Bidirectional Forwarding Detection",
draft-katz-ward-bfd-01.txt (work in progress).
9. Author's Addresses
Zafar Ali
Cisco Systems Inc.
100 South Main St. #200
Ann Arbor, MI 48104, USA.
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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: dprairie@cisco.com
Danny Prairie
Cisco Systems Inc.
2000 Innovation Dr.,
Kanata, Ontario, K2K 3E8, Canada.
Phone: (613)-254-3519
Email: rrahman@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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