BGP Multipath in Inter-AS Option-B
draft-mohanty-bess-mutipath-interas-01

Document Type Active Internet-Draft (individual)
Last updated 2017-09-11
Stream (None)
Intended RFC status (None)
Formats plain text xml pdf html 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)
BESS WorkGroup                                                S. Mohanty
Internet-Draft                                            A. Sreekantiah
Intended status: Informational                                    D. Rao
Expires: March 14, 2018                                    Cisco Systems
                                                                K. Patel
                                                             Arrcus, Inc
                                                      September 10, 2017

                   BGP Multipath in Inter-AS Option-B
                 draft-mohanty-bess-mutipath-interas-01

Abstract

   By default, The Border Gateway Protocol, BGP only installs the best-
   path to the IP Routing Table.  BGP multi-path is a well known feature
   that enables installation of multiple paths to the IP Routing Table.
   This is done to achieve load balancing while forwarding traffic.  For
   a path to be eligible as a multi-path, certain criteria need to be
   fulfilled.  Inter-AS VPNs are commonly deployed to span organizations
   across Service Provider boundaries.  In this draft, we describe an
   issue relating to multi-path load balancing that can arise in an
   Option B Inter-AS Deployment.  With the help of a representative
   topology, we illustrate the problem and then present two simple
   schemes as the solution to the problem.  We also note as a matter of
   independent interest that the same underlying issue is applicable to
   deployments that employ next-hop-self behavior (implicit or explicit)
   downstream and the multi-path feature upstream.

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 https://datatracker.ietf.org/drafts/current/.

   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 March 14, 2018.

Mohanty, et al.          Expires March 14, 2018                 [Page 1]
Internet-Draft     BGP Multipath in Inter-AS Option-B     September 2017

Copyright Notice

   Copyright (c) 2017 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
   (https://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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Topology notation . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Problem Description . . . . . . . . . . . . . . . . . . . . .   4
   5.  BGP ADDpath with the non-unique RD case . . . . . . . . . . .   4
   6.  BGP Labeled unicast with Add-Path . . . . . . . . . . . . . .   5
   7.  BGP Multi-path Inter-As Solution 1  . . . . . . . . . . . . .   5
   8.  BGP Multi-path Inter-As Solution 2  . . . . . . . . . . . . .   5
   9.  Protocol Considerations . . . . . . . . . . . . . . . . . . .   6
   10. Operational Considerations  . . . . . . . . . . . . . . . . .   6
   11. Security Considerations . . . . . . . . . . . . . . . . . . .   6
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     13.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     13.2.  Informative References . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   By Default BGP [RFC4271] only advertises the best-path to a peer and
   also installs the best-path to the IP Routing Table (RIB) and thereby
   to the Forwarding Information Base (FIB).  BGP multi-path is a
   feature where more than one received BGP route, rather than only the
   one corresponding to the BGP best-path, are installed in the IP
   Routing Table and the Forwarding Information Base.  This offers
   benefits of load balancing, efficient utilization of system resources
Show full document text