draft-ietf-idr-best-external-01.txt   draft-ietf-idr-best-external-02.txt 
Network Working Group P. Marques Network Working Group P. Marques
Internet-Draft R. Fernando Internet-Draft R. Fernando
Intended status: Standards Track E. Chen Intended status: Standards Track E. Chen
Expires: August 8, 2010 P. Mohapatra Expires: February 8, 2011 P. Mohapatra
Cisco Systems Cisco Systems
February 4, 2010 August 7, 2010
Advertisement of the best external route in BGP Advertisement of the best external route in BGP
draft-ietf-idr-best-external-01.txt draft-ietf-idr-best-external-02.txt
Abstract Abstract
The base BGP specifications prevent a BGP speaker from advertising The base BGP specifications prevent a BGP speaker from advertising
any route that is not the best route for a BGP destination. This any route that is not the best route for a BGP destination. This
document specifies a modification of this rule. Routes are divided document specifies a modification of this rule. Routes are divided
into two categories, "external" and "internal". A specification is into two categories, "external" and "internal". A specification is
provided for choosing a "best external route" (for a particular value provided for choosing a "best external route" (for a particular value
of the Network Layer Reachability Information). A BGP speaker is of the Network Layer Reachability Information). A BGP speaker is
then allowed to advertise its "best external route" to its internal then allowed to advertise its "best external route" to its internal
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 8, 2010. This Internet-Draft will expire on February 8, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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modifications of such material outside the IETF Standards Process. modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Algorithm for selection of best external route . . . . . . . . 4 2. Algorithm for selection of best external route . . . . . . . . 5
3. Advertisement Rules . . . . . . . . . . . . . . . . . . . . . . 5 3. Advertisement Rules . . . . . . . . . . . . . . . . . . . . . 6
4. Consistency between routing and forwarding . . . . . . . . . . 5 4. Consistency between routing and forwarding . . . . . . . . . . 6
5. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Fast Connectivity Restoration . . . . . . . . . . . . . . . 7 5.1. Fast Connectivity Restoration . . . . . . . . . . . . . . 8
5.2. Inter-Domain Churn Reduction . . . . . . . . . . . . . . . 8 5.2. Inter-Domain Churn Reduction . . . . . . . . . . . . . . . 9
5.3. Reducing Persistent IBGP oscillation . . . . . . . . . . . 8 5.3. Reducing Persistent IBGP oscillation . . . . . . . . . . . 9
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. Normative References . . . . . . . . . . . . . . . . . . . . . 8 9. Normative References . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
The base BGP specifications prevent a BGP speaker from advertising The base BGP specifications prevent a BGP speaker from advertising
any route that is not the best route for a BGP destination. This any route that is not the best route for a BGP destination. This
document specifies a modification of this rule. Routes are divided document specifies a modification of this rule. Routes are divided
into two categories, "external" and "internal". A specification is into two categories, "external" and "internal". A specification is
provided for choosing a "best external route" (for a particular value provided for choosing a "best external route" (for a particular value
of the Network Layer Reachability Information). A BGP speaker is of the Network Layer Reachability Information). A BGP speaker is
then allowed to advertise its "best external route" to its internal then allowed to advertise its "best external route" to its internal
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