North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP
RFC 7752

Document Type RFC - Proposed Standard (March 2016; No errata)
Last updated 2016-03-16
Replaces draft-gredler-idr-ls-distribution
Stream IETF
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Stream WG state Submitted to IESG for Publication
Document shepherd Jie Dong
Shepherd write-up Show (last changed 2015-10-08)
IESG IESG state RFC 7752 (Proposed Standard)
Consensus Boilerplate Yes
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Responsible AD Alvaro Retana
Send notices to aretana@cisco.com
IANA IANA review state Version Changed - Review Needed
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                   H. Gredler, Ed.
Request for Comments: 7752                        Individual Contributor
Category: Standards Track                                      J. Medved
ISSN: 2070-1721                                               S. Previdi
                                                     Cisco Systems, Inc.
                                                               A. Farrel
                                                  Juniper Networks, Inc.
                                                                  S. Ray
                                                              March 2016

  North-Bound Distribution of Link-State and Traffic Engineering (TE)
                         Information Using BGP

Abstract

   In a number of environments, a component external to a network is
   called upon to perform computations based on the network topology and
   current state of the connections within the network, including
   Traffic Engineering (TE) information.  This is information typically
   distributed by IGP routing protocols within the network.

   This document describes a mechanism by which link-state and TE
   information can be collected from networks and shared with external
   components using the BGP routing protocol.  This is achieved using a
   new BGP Network Layer Reachability Information (NLRI) encoding
   format.  The mechanism is applicable to physical and virtual IGP
   links.  The mechanism described is subject to policy control.

   Applications of this technique include Application-Layer Traffic
   Optimization (ALTO) servers and Path Computation Elements (PCEs).

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7752.

Gredler, et al.              Standards Track                    [Page 1]
RFC 7752         Link-State Info Distribution Using BGP       March 2016

Copyright Notice

   Copyright (c) 2016 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
   (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
   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.

Table of Contents

   1. Introduction ....................................................3
      1.1. Requirements Language ......................................5
   2. Motivation and Applicability ....................................5
      2.1. MPLS-TE with PCE ...........................................5
      2.2. ALTO Server Network API ....................................6
   3. Carrying Link-State Information in BGP ..........................7
      3.1. TLV Format .................................................8
      3.2. The Link-State NLRI ........................................8
           3.2.1. Node Descriptors ...................................12
           3.2.2. Link Descriptors ...................................16
           3.2.3. Prefix Descriptors .................................18
      3.3. The BGP-LS Attribute ......................................19
           3.3.1. Node Attribute TLVs ................................20
           3.3.2. Link Attribute TLVs ................................23
           3.3.3. Prefix Attribute TLVs ..............................28
      3.4. BGP Next-Hop Information ..................................31
      3.5. Inter-AS Links ............................................32
      3.6. Router-ID Anchoring Example: ISO Pseudonode ...............32
      3.7. Router-ID Anchoring Example: OSPF Pseudonode ..............33
      3.8. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration ....34
   4. Link to Path Aggregation .......................................34
      4.1. Example: No Link Aggregation ..............................35
      4.2. Example: ASBR to ASBR Path Aggregation ....................35
      4.3. Example: Multi-AS Path Aggregation ........................36
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