Clarifications to RFC 5884
draft-ietf-bfd-rfc5884-clarifications-02

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Document Type Active Internet-Draft (bfd WG)
Last updated 2015-09-25 (latest revision 2015-06-16)
Replaces draft-grmas-bfd-rfc5884-clarifications
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Send notices to "Jeffrey Haas" <jhaas@pfrc.org>, draft-ietf-bfd-rfc5884-clarifications@ietf.org, bfd-chairs@ietf.org
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Internet Engineering Task Force                              V. Govindan
Internet-Draft                                              K. Rajaraman
Updates: 5884 (if approved)                                Cisco Systems
Intended status: Standards Track                               G. Mirsky
Expires: December 18, 2015                                      Ericsson
                                                                N. Akiya
                                                     Big Switch Networks
                                                               S. Aldrin
                                                                  Google
                                                           June 16, 2015

                       Clarifications to RFC 5884
                draft-ietf-bfd-rfc5884-clarifications-02

Abstract

   This document clarifies the procedures for establishing, maintaining
   and removing multiple, concurrent BFD sessions for a given <MPLS LSP,
   FEC> described in RFC5884.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on December 18, 2015.

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   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

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Internet-Draft         Clarifications to RFC 5884              June 2015

   to this document.  Code Components extracted from this document must
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Theory of Operation . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Procedures for establishment of multiple BFD sessions . .   3
     2.2.  Procedures for maintenance of multiple BFD sessions . . .   4
     2.3.  Procedures for removing BFD sessions at the egress LSR  .   4
     2.4.  Changing discriminators for a BFD session . . . . . . . .   4
   3.  Backwards Compatibility . . . . . . . . . . . . . . . . . . .   5
   4.  Encapsulation . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Background

   [RFC5884] defines the procedures to bootstrap and maintain BFD
   sessions for a <MPLS FEC, LSP> using LSP ping.  While Section 4 of
   [RFC5884] specifies that multiple BFD sessions can be established for
   a <MPLS FEC, LSP> tuple, the procedures to bootstrap and maintain
   multiple BFD sessions concurrently over a <MPLS FEC, LSP> are not
   clearly specified.  Additionally, the procedures of removing BFD
   sessions bootstrapped on the egress LSR are unclear.  This document
   provides those clarifications without deviating from the principles
   outlined in [RFC5884].

   The ability for an ingress LSR to establish multiple BFD sessions for
   a <MPLS FEC, LSP> tuple is useful in scenarios such as Segment
   Routing based LSPs or LSPs having Equal-Cost Multipath (ECMP).  The
   process used by the ingress LSR to determine the number of BFD
   session(s) to be bootstrapped for a <MPLS FEC, LSP> tuple and the
   mechanism of constructing those session(s) are outside the scope of
   this document.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

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