--- 1/draft-ietf-idr-best-external-00.txt 2010-02-04 18:10:45.000000000 +0100 +++ 2/draft-ietf-idr-best-external-01.txt 2010-02-04 18:10:45.000000000 +0100 @@ -1,99 +1,104 @@ Network Working Group P. Marques Internet-Draft R. Fernando -Intended status: Standards Track Juniper Networks -Expires: November 15, 2009 E. Chen - P. Mohapatra +Intended status: Standards Track E. Chen +Expires: August 8, 2010 P. Mohapatra Cisco Systems - May 14, 2009 + February 4, 2010 Advertisement of the best external route in BGP - draft-ietf-idr-best-external-00.txt + draft-ietf-idr-best-external-01.txt + +Abstract + + The base BGP specifications prevent a BGP speaker from advertising + any route that is not the best route for a BGP destination. This + document specifies a modification of this rule. Routes are divided + into two categories, "external" and "internal". A specification is + provided for choosing a "best external route" (for a particular value + of the Network Layer Reachability Information). A BGP speaker is + then allowed to advertise its "best external route" to its internal + BGP peers, even if that is not the best route for the destination. + The document explains why advertising the best external route can + improve convergence time without causing routing loops. Additional + benefits include reduction of inter-domain churn and avoidance of + permanent route oscillation. The document also generalizes the + notions of "internal" and "external" so that they can be applied to + Route Reflector Clusters and Autonomous System Confederations. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the - provisions of BCP 78 and BCP 79. This document may contain material - from IETF Documents or IETF Contributions published or made publicly - available before November 10, 2008. The person(s) controlling the - copyright in some of this material may not have granted the IETF - Trust the right to allow modifications of such material outside the - IETF Standards Process. Without obtaining an adequate license from - the person(s) controlling the copyright in such materials, this - document may not be modified outside the IETF Standards Process, and - derivative works of it may not be created outside the IETF Standards - Process, except to format it for publication as an RFC or to - translate it into languages other than English. + provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on November 15, 2009. + This Internet-Draft will expire on August 8, 2010. Copyright Notice - Copyright (c) 2009 IETF Trust and the persons identified as the + Copyright (c) 2010 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 in effect on the date of - publication of this document (http://trustee.ietf.org/license-info). - Please review these documents carefully, as they describe your rights - and restrictions with respect to this document. - -Abstract + 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 BSD License. - The base BGP specifications prevent a BGP speaker from advertising - any route that is not the best route for a BGP destination. This - document specifies a modification of this rule. Routes are divided - into two categories, "external" and "internal". A specification is - provided for choosing a "best external route" (for a particular value - of the Network Layer Reachability Information). A BGP speaker is - then allowed to advertise its "best external route" to its internal - BGP peers, even if that is not the best route for the destination. - The document explains why advertising the best external route can - improve convergence time without causing routing loops. Additional - benefits include reduction of inter-domain churn and avoidance of - permanent route oscillation. The document also generalizes the - notions of "internal" and "external" so that they can be applied to - Route Reflector Clusters and Autonomous System Confederations. + This document may contain material from IETF Documents or IETF + Contributions published or made publicly available before November + 10, 2008. The person(s) controlling the copyright in some of this + material may not have granted the IETF Trust the right to allow + modifications of such material outside the IETF Standards Process. + Without obtaining an adequate license from the person(s) controlling + the copyright in such materials, this document may not be modified + outside the IETF Standards Process, and derivative works of it may + not be created outside the IETF Standards Process, except to format + it for publication as an RFC or to translate it into languages other + than English. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 - 2. Algorithm for selection of best external route . . . . . . . . 5 - 3. Advertisement Rules . . . . . . . . . . . . . . . . . . . . . 6 - 4. Consistency between routing and forwarding . . . . . . . . . . 6 - 5. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 5.1. Fast Connectivity Restoration . . . . . . . . . . . . . . 8 - 5.2. Inter-Domain Churn Reduction . . . . . . . . . . . . . . . 9 - 5.3. Reducing Persistent IBGP oscillation . . . . . . . . . . . 9 - 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 - 9. Normative References . . . . . . . . . . . . . . . . . . . . . 9 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 + 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 4 + 2. Algorithm for selection of best external route . . . . . . . . 4 + 3. Advertisement Rules . . . . . . . . . . . . . . . . . . . . . . 5 + 4. Consistency between routing and forwarding . . . . . . . . . . 5 + 5. Applications . . . . . . . . . . . . . . . . . . . . . . . . . 7 + 5.1. Fast Connectivity Restoration . . . . . . . . . . . . . . . 7 + 5.2. Inter-Domain Churn Reduction . . . . . . . . . . . . . . . 8 + 5.3. Reducing Persistent IBGP oscillation . . . . . . . . . . . 8 + 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 + 9. Normative References . . . . . . . . . . . . . . . . . . . . . 8 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction The base BGP specifications prevent a BGP speaker from advertising any route that is not the best route for a BGP destination. This document specifies a modification of this rule. Routes are divided into two categories, "external" and "internal". A specification is provided for choosing a "best external route" (for a particular value of the Network Layer Reachability Information). A BGP speaker is then allowed to advertise its "best external route" to its internal @@ -371,36 +376,36 @@ [RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route Reflection: An Alternative to Full Mesh Internal BGP (IBGP)", RFC 4456, April 2006. [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous System Confederations for BGP", RFC 5065, August 2007. Authors' Addresses Pedro Marques - Juniper Networks - 1194 N. Mathilda Ave - Sunnyvale, CA 94089 + Cisco Systems + 170 W. Tasman Drive + San Jose, CA 95134 USA Phone: - Email: roque@juniper.net + Email: roque@cisco.com Rex Fernando - Juniper Networks - 1194 N. Mathilda Ave - Sunnyvale, CA 94089 + Cisco Systems + 170 W. Tasman Drive + San Jose, CA 95134 USA Phone: - Email: rex@juniper.net + Email: rex@cisco.com Enke Chen Cisco Systems 170 W. Tasman Drive San Jose, CA 95134 USA Phone: Email: enkechen@cisco.com Pradosh Mohapatra