Distribution of Link-State and Traffic Engineering Information Using BGP
draft-ietf-idr-rfc7752bis-01

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Last updated 2019-09-14
Replaces draft-ketant-idr-rfc7752bis
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Inter-Domain Routing                                  K. Talaulikar, Ed.
Internet-Draft                                             Cisco Systems
Obsoletes: 7752 (if approved)                         September 14, 2019
Intended status: Standards Track
Expires: March 17, 2020

Distribution of Link-State and Traffic Engineering Information Using BGP
                      draft-ietf-idr-rfc7752bis-01

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).

   This document obsoletes RFC 7752 by completely replacing that
   document.  It makes a number of small changes and clarifications to
   the previous specification.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 17, 2020.

Talaulikar               Expires March 17, 2020                 [Page 1]
Internet-Draft   Link-State Info Distribution Using BGP   September 2019

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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 . . . . . . . . . . . . . . . . .   7
   3.  BGP Speaker Roles for BGP-LS  . . . . . . . . . . . . . . . .   7
   4.  Carrying Link-State Information in BGP  . . . . . . . . . . .   9
     4.1.  TLV Format  . . . . . . . . . . . . . . . . . . . . . . .   9
     4.2.  The Link-State NLRI . . . . . . . . . . . . . . . . . . .  10
       4.2.1.  Node Descriptors  . . . . . . . . . . . . . . . . . .  14
       4.2.2.  Link Descriptors  . . . . . . . . . . . . . . . . . .  18
       4.2.3.  Prefix Descriptors  . . . . . . . . . . . . . . . . .  21
     4.3.  The BGP-LS Attribute  . . . . . . . . . . . . . . . . . .  22
       4.3.1.  Node Attribute TLVs . . . . . . . . . . . . . . . . .  23
       4.3.2.  Link Attribute TLVs . . . . . . . . . . . . . . . . .  26
       4.3.3.  Prefix Attribute TLVs . . . . . . . . . . . . . . . .  31
     4.4.  Private Use . . . . . . . . . . . . . . . . . . . . . . .  34
     4.5.  BGP Next-Hop Information  . . . . . . . . . . . . . . . .  35
     4.6.  Inter-AS Links  . . . . . . . . . . . . . . . . . . . . .  35
     4.7.  Handling of Unreachable IGP Nodes . . . . . . . . . . . .  36
     4.8.  Router-ID Anchoring Example: ISO Pseudonode . . . . . . .  37
     4.9.  Router-ID Anchoring Example: OSPF Pseudonode  . . . . . .  38
     4.10. Router-ID Anchoring Example: OSPFv2 to IS-IS Migration  .  39
   5.  Link to Path Aggregation  . . . . . . . . . . . . . . . . . .  40
     5.1.  Example: No Link Aggregation  . . . . . . . . . . . . . .  40
     5.2.  Example: ASBR to ASBR Path Aggregation  . . . . . . . . .  40
     5.3.  Example: Multi-AS Path Aggregation  . . . . . . . . . . .  41
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