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Node-ID Based Resource Reservation Protocol (RSVP) Hello: A Clarification Statement
RFC 4558

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

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