draft-ietf-idr-rfc3065bis-00.txt   draft-ietf-idr-rfc3065bis-01.txt 
INTERNET-DRAFT Paul Traina INTERNET-DRAFT Paul Traina
draft-ietf-idr-rfc3065bis-00.txt Danny McPherson Danny McPherson
Arbor Networks Arbor Networks
John Scudder John Scudder
Cisco Systems Cisco Systems
Expires: February 2004 August 2003 Expires: April 2004 October 2003
Autonomous System Confederations for BGP Autonomous System Confederations for BGP
<draft-ietf-idr-rfc3065bis-00.txt> <draft-ietf-idr-rfc3065bis-01.txt>
Status of this Document Status of this Document
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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5. Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. AS_PATH Modification Rules. . . . . . . . . . . . . . . . . 7 5.1. AS_PATH Modification Rules. . . . . . . . . . . . . . . . . 7
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Common Administration Issues . . . . . . . . . . . . . . . . . 9 7. Common Administration Issues . . . . . . . . . . . . . . . . . 9
7.1. MED and LOCAL_PREF Handling . . . . . . . . . . . . . . . . 9 7.1. MED and LOCAL_PREF Handling . . . . . . . . . . . . . . . . 9
7.2. AS_PATH and Path Selection. . . . . . . . . . . . . . . . . 9 7.2. AS_PATH and Path Selection. . . . . . . . . . . . . . . . . 9
8. Compatability Considerations . . . . . . . . . . . . . . . . . 10 8. Compatability Considerations . . . . . . . . . . . . . . . . . 10
9. Deployment Considerations. . . . . . . . . . . . . . . . . . . 10 9. Deployment Considerations. . . . . . . . . . . . . . . . . . . 10
10. Intellectual Property . . . . . . . . . . . . . . . . . . . . 11 10. Intellectual Property . . . . . . . . . . . . . . . . . . . . 11
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
12. Security Considerations . . . . . . . . . . . . . . . . . . . 13 12. Security Considerations . . . . . . . . . . . . . . . . . . . 12
13. References. . . . . . . . . . . . . . . . . . . . . . . . . . 14 13. References. . . . . . . . . . . . . . . . . . . . . . . . . . 13
14. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . 15 14. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . 14
15. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 15 15. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
As currently defined, BGP requires that all BGP speakers within a As currently defined, BGP requires that all BGP speakers within a
single AS must be fully meshed. The result is that for n BGP single AS must be fully meshed. The result is that for n BGP
speakers within an AS n*(n-1)/2 unique IBGP sessions are required. speakers within an AS n*(n-1)/2 unique IBGP sessions are required.
This "full mesh" requirement clearly does not scale when there are a This "full mesh" requirement clearly does not scale when there are a
large number of IBGP speakers within the autonomous system, as is large number of IBGP speakers within the autonomous system, as is
common in many networks today. common in many networks today.
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Path selection criteria for information received from members inside Path selection criteria for information received from members inside
a confederation MUST follow the same rules used for information a confederation MUST follow the same rules used for information
received from members inside the same autonomous system, as specified received from members inside the same autonomous system, as specified
in [1]. in [1].
In addition, the following rules SHALL be applied: In addition, the following rules SHALL be applied:
1) If the AS_PATH is internal to the local confederation (i.e., there 1) If the AS_PATH is internal to the local confederation (i.e., there
are only AS_CONFED_* segments) consider the neighbor AS to be the are only AS_CONFED_* segments) consider the neighbor AS to be the
leftmost AS_CONFED_SEQUENCE AS. local AS.
2) If the AS_PATH is external to the local confederation (i.e., there
are one or more non-AS_CONFED_* segments) consider the neighbor AS
to be the leftmost AS_SEQUENCE AS.
An AS of the first type SHALL NOT be compared to an AS of the second 2) Otherwise, if the first segment in the path which is not an
type (i.e., they are from different namespaces even if the values are AS_CONFED_SEQUENCE or AS_CONFED_SET is an AS_SEQUENCE, consider
identical). the neighbor AS to be the leftmost AS_SEQUENCE AS.
8. Compatability Considerations 8. Compatability Considerations
All BGP speakers participating as member of a confederation MUST All BGP speakers participating as member of a confederation MUST
recognize the AS_CONFED_SET and AS_CONFED_SEQUENCE segment type recognize the AS_CONFED_SET and AS_CONFED_SEQUENCE segment type
extensions to the AS_PATH attribute. extensions to the AS_PATH attribute.
Any BGP speaker not supporting these extensions will generate a Any BGP speaker not supporting these extensions will generate a
NOTIFICATION message specifying an "UPDATE Message Error" and a sub- NOTIFICATION message specifying an "UPDATE Message Error" and a sub-
code of "Malformed AS_PATH". code of "Malformed AS_PATH".
 End of changes. 

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