Carry congestion status in BGP extended community
draft-li-idr-congestion-status-extended-community-05

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Last updated 2017-06-30
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IDR                                                                Z. Li
Internet-Draft                                              China Mobile
Updates: 4271, 4360, 7153 (if approved)                          J. Dong
Intended status: Experimental                        Huawei Technologies
Expires: January 1, 2018                                   June 30, 2017

           Carry congestion status in BGP extended community
          draft-li-idr-congestion-status-extended-community-05

Abstract

   A new extended community, called congestion status extended
   community, is introduced in this document to carry the link
   congestion status, especially for the exit link of one AS.
   Congestion status extended community can be used by the BGP speakers
   to steer the AS-outgoing traffic among the exit links.

Requirements Language

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

Status of This Memo

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

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   This Internet-Draft will expire on January 1, 2018.

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

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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Congestion Status Extended Community  . . . . . . . . . . . .   4
   3.  Application Considerations  . . . . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Knowing the congestion status of the AS exit links is useful for
   traffic steering, especially for steering the AS outgoing traffic
   among the exit links.

   AS A, as shown in the following figure, has multiple exit links
   connected to AS B.  Both AS A and B has exit link to AS C, and AS B
   provides transit service for AS A.  Due to cost or some other
   reasons, AS A prefers using AS B to transmit its' traffic to AS C,
   not the directly connected link between AS A and C.  If the exit
   routers, Router 7 and 8, in AS A tell their iBGP peers the congestion
   status of the exit links, the peers in turn can steer some outgoing
   traffic toward the less loaded exit link.  If AS A knows the link
   between AS B and AS C is congested, it can steer some traffic towards
   AS C from AS B to the directly connected link by applying some route
   policies.

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     +-------------------------------------------+
     |                   AS C                    |
     |  +----------+               +----------+  |
     +--| Router 1 |---------------| Router 2 |--+
        +----------+               +----------+
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