BGP trigger Segment Routing ODN

The information below is for an old version of the document
Document Type Active Internet-Draft (individual)
Last updated 2018-10-01
Stream (None)
Intended RFC status (None)
Formats pdf htmlized bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
Network Working Group                                        Yuanchao Su
Internet-Draft                                               Cisco Systems, Inc.
Intended status: Standards Track                             October 1,2018 
Expires: January 3, 2019                                    

              BGP trigger Segment Routing ODN


   This document defines an extension to the BGP SR Policy NLRI
   (draft-ietf-idr-segment-routing-te-policy) in order to use BGP to trigger 
   Segment Routing ODN, without using PCEP.
   The goal is to consolidate the SR Policy provision(BGP-TE), collection(BGP-LS)
   and ODN-trigger protocol for device to be BGP only, thus remove the need
   for PCEP and reduce the network complexity and potential bugs cause by
   different protocol interactions.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 3, 2019.

Copyright Notice

   Copyright (c) 2018 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
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   Segment Routing (SR) allows a headend node to steer a packet flow
   along any path.  Intermediate per-flow states are eliminated thanks
   to source routing [I-D.ietf-spring-segment-routing].

   The headend node is said to steer a flow into a Segment Routing
   Policy (SR Policy).

   The header of a packet steered in an SR Policy is augmented with the
   ordered list of segments associated with that SR Policy.

   [I-D.ietf-spring-segment-routing-policy] details the concepts of SR
   Policy and steering into an SR Policy.  These apply equally to the
   MPLS and SRv6 instantiations of segment routing.

   [I-D.ietf-idr-segment-routing-te-policy] specifies the way to use BGP
   to distribute one or more of the candidate paths of an SR Policy to the
   headend of that policy.
   This document specifies a way for headend to trigger SR ODN with BGP SR Policy NLRI UPDATE messages.
   BGP can then be used to replace PCEP as the signal protocol for ODN.
   This special UPDATE message SHOULD NOT be used for BGP best path selection.
   When controller receives this specific UPDATE message from headend, it checks whether it's PCE,
   if yes, it processed the payload of the message, otherwise it drops the message.
   If controller is PCE, it retrieves the color, link affinity, association
   information from the message and starts the path calculation.
   Once the path calculation is done, the controller uses BGP SR Policy NLRI UPDATE message
   to distribute the candidate path to headend.If the calculation is failed, 
   for example, the constrains expressed by the link affinity TLV can't be met, 
   the controller MUST sends a BGP SR Policy NLRI with Segment List TLV empty and Bing-SID empty.
   When headend receives the update from controller, it processed the update
   as specified in [I-D.ietf-idr-segment-routing-te-policy]

   The extensions to SR Policy NLRI include:

   o  Distinguisher field SR Policy NLRI: special address FF:FF:FF:FF as the signal for ODN

   o  Two new sub-TLVs belong to Tunnel Encaps Attribute with Tunnel-Type set to 15(SR Policy) 
      o Metric sub-TLV to specify the metric that the PCE should use for the path calculation
      o Link Affinity sub-TLV to specify the link constrains
      o Association sub-TLV to specify the disjointness and protection constrains

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  BGP trigger ODN Encoding
Show full document text