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Keywords: [--------|p], Multi-Protocol Label Switching, mpls, Generalized Multi-Protocol Label Switching, gmpls, Traffic Engineering, te, rsvp-te, gr, graceful restart
Network Working Group Z. Ali
Request for Comments: 4558 R. Rahman
Category: Standards Track D. Prairie
Cisco Systems
D. Papadimitriou
Alcatel
June 2006
Node-ID Based Resource Reservation Protocol (RSVP) Hello:
A Clarification Statement
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
Use of Node-ID based Resource Reservation Protocol (RSVP) Hello
messages is implied in a number of cases, e.g., when data and control
planes are separated, when TE links are unnumbered. Furthermore,
when link level failure detection is performed by some means other
than exchanging RSVP Hello messages, use of a Node-ID based Hello
session is optimal for detecting signaling adjacency failure for
Resource reSerVation Protocol-Traffic Engineering (RSVP-TE).
Nonetheless, this implied behavior is unclear, and this document
formalizes use of the 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.
Ali, et al. Standards Track [Page 1]
RFC 4558 Node-ID Based RSVP Hello June 2006
1. Introduction
The RSVP Hello message exchange was introduced in [RFC3209]. The
usage of RSVP Hello has been extended in [RFC3473] to support RSVP
Graceful Restart (GR) procedures.
More specifically, [RFC3473] 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
that 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 applications introduces a need for clarifying the
behavior and usage of Node-ID based Hello sessions.
Even in the case of packet switching capable interfaces, 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 and 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.
2. 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 in which 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 in which local and
remote addresses of the interface in question are used in the source
and destination fields of the Hello packet, respectively.
Ali, et al. Standards Track [Page 2]
RFC 4558 Node-ID Based RSVP Hello June 2006
2.1. 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].
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, for IPv4, Node-ID refers 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 interfaces, 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
and 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 an
optical network with single or multiple numbered or unnumbered
control channels, use 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 a 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,
Ali, et al. Standards Track [Page 3]
RFC 4558 Node-ID Based RSVP Hello June 2006
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 [RFC3209], 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 [RFC3473] (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.
Ali, et al. Standards Track [Page 4]
RFC 4558 Node-ID Based RSVP Hello June 2006
7. Reference
7.1. Normative References
[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 M. Talwar, "RSVP
Cryptographic Authentication", RFC 2747, January 2000.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January
2003.
7.2. Informative References
[OSPF-TE] Katz, D., Kompella, K., and D. Yeung, "Traffic
Engineering (TE) Extensions to OSPF Version 2", RFC
3630, September 2003.
[ISIS-TE] Smit, H. and T. Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE)",
RFC 3784, June 2004.
[BFD] Katz, D. and D. Ward, "Bidirectional Forwarding
Detection", Work in Progress.
[IS-ISv6-TE] Harrison, J., et al. "IPv6 Traffic Engineering in IS-
IS", Work in Progress, November 2005.
[OSPFv3-TE] Ishiguro, K., et al. "Traffic Engineering Extensions to
OSPF version 3", Work in Progress, April 2006.
Ali, et al. Standards Track [Page 5]
RFC 4558 Node-ID Based RSVP Hello June 2006
Authors' Addresses
Zafar Ali
Cisco Systems Inc.
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) 254-3544
EMail: dprairie@cisco.com
Dimitri Papadimitriou
Alcatel
Fr. Wellesplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 240-8491
EMail: dimitri.papadimitriou@alcatel.be
Ali, et al. Standards Track [Page 6]
RFC 4558 Node-ID Based RSVP Hello June 2006
Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
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Ali, et al. Standards Track [Page 7]