draft-ietf-idr-bgp-confed-00.txt   rfc1965.txt 
Internet Engineering Task Force Paul Traina Network Working Group P. Traina
INTERNET DRAFT cisco Systems Request for Comments: 1965 cisco Systems
<draft-ietf-idr-bgp-confed-00.txt> March 27, 1996 Category: Experimental June 1996
Autonomous System Confederations for BGP Autonomous System Confederations for BGP
Status of this Memo Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard. Distribution of this memo is
unlimited.
This document is an Internet Draft. 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. Internet Drafts may be updated, replaced, or obsoleted by
other documents at any time. It is not appropriate to use Internet
Drafts as reference material or to cite them other than as a "working
draft" or "work in progress."
Please check the I-D abstract listing contained in each Internet This memo defines an Experimental Protocol for the Internet
Draft directory to learn the current status of this or any other community. This memo does not specify an Internet standard of any
Internet Draft. kind. Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Abstract Abstract
Border Gateway Protocol [1] is an inter-autonomous system routing Border Gateway Protocol [1] is an inter-autonomous system routing
protocol designed for TCP/IP networks. protocol designed for TCP/IP networks.
This document describes an extension to BGP which may be used to This document describes an extension to BGP which may be used to
create a confederation of autonomous systems which is represented as create a confederation of autonomous systems which is represented as
one single autonomous system to BGP peers external to the one single autonomous system to BGP peers external to the
confederation. confederation.
skipping to change at page 4, line 44 skipping to change at page 4, line 21
Section 5.1.2 of [1] is replaced with the following text. Section 5.1.2 of [1] is replaced with the following text.
When a BGP speaker propagates a route which it has learned from When a BGP speaker propagates a route which it has learned from
another BGP speaker's UPDATE message, it shall modify the route's another BGP speaker's UPDATE message, it shall modify the route's
AS_PATH attribute based on the location of the BGP speaker to which AS_PATH attribute based on the location of the BGP speaker to which
the route will be sent: the route will be sent:
a) When a given BGP speaker advertises the route to another BGP a) When a given BGP speaker advertises the route to another BGP
speaker located in its own autonomous system, the advertising speaker located in its own autonomous system, the advertising
speaker shall not modify the AS_PATH attribute associated with the speaker shall not modify the AS_PATH attribute associated with
route. the route.
b) When a given BGP speaker advertises the route to a BGP speaker b) When a given BGP speaker advertises the route to a BGP
located in a neighboring autonomous system that is a member of the speaker located in a neighboring autonomous system that is a
local autonomous system confederation, then the advertising member of the local autonomous system confederation, then the
speaker shall update the AS_PATH attribute as follows: advertising speaker shall update the AS_PATH attribute as
follows:
1) if the first path segment of the AS_PATH is of type 1) if the first path segment of the AS_PATH is of type
AS_CONFED_SEQUENCE, the local system shall prepend its own AS AS_CONFED_SEQUENCE, the local system shall prepend its own AS
number as the last element of the sequence (put it in the number as the last element of the sequence (put it in the
leftmost position). leftmost position).
2) if the first path segment of the AS_PATH is not of type 2) if the first path segment of the AS_PATH is not of type
AS_CONFED_SEQUENCE the local system shall prepend a new path AS_CONFED_SEQUENCE the local system shall prepend a new path
segment of type AS_CONFED_SEQUENCE to the AS_PATH, including segment of type AS_CONFED_SEQUENCE to the AS_PATH, including
its own confederation identifier in that segment. its own confederation identifier in that segment.
c) When a given BGP speaker advertises the route to a BGP speaker c) When a given BGP speaker advertises the route to a BGP
located in a neighboring autonomous system that is not a member of speaker located in a neighboring autonomous system that is not a
the current routing domain confederation, then the advertising member of the current routing domain confederation, then the
speaker shall update the AS_PATH attribute as follows: advertising speaker shall update the AS_PATH attribute as
follows:
1) if the first path segment of the AS_PATH is of type 1) if the first path segment of the AS_PATH is of type
AS_CONFED_SEQUENCE, that segment and any immediately following AS_CONFED_SEQUENCE, that segment and any immediately
segments of the type AS_CONFED_SET are removed from the AS_PATH following segments of the type AS_CONFED_SET are removed from
attribute, leaving the sanitized AS_PATH attribute to be the AS_PATH attribute, leaving the sanitized AS_PATH
operated on by steps 2, or 3. attribute to be operated on by steps 2, or 3.
2) if the first path segment of the remaining AS_PATH is of 2) if the first path segment of the remaining AS_PATH is of
type AS_SEQUENCE, the local system shall prepend its own type AS_SEQUENCE, the local system shall prepend its own
confederation identifier as the last element of the sequence confederation identifier as the last element of the sequence
(put it in the leftmost position). (put it in the leftmost position).
3) if there are no path segments following the removal of the 3) if there are no path segments following the removal of the
first AS_CONFED_SET/AS_CONFED_SEQUENCE segments, or if the first AS_CONFED_SET/AS_CONFED_SEQUENCE segments, or if the
first path segment of the remaining AS_PATH is of type AS_SET first path segment of the remaining AS_PATH is of type AS_SET
the local system shall prepend a new path segment of type the local system shall prepend a new path segment of type
skipping to change at page 5, line 47 skipping to change at page 5, line 25
identifier in that segment. identifier in that segment.
When a BGP speaker originates a route: When a BGP speaker originates a route:
a) the originating speaker shall include an empty AS_PATH a) the originating speaker shall include an empty AS_PATH
attribute in all UPDATE messages sent to BGP speakers located in attribute in all UPDATE messages sent to BGP speakers located in
its own autonomous system. (An empty AS_PATH attribute is one its own autonomous system. (An empty AS_PATH attribute is one
whose length field contains the value zero). whose length field contains the value zero).
b) the originating speaker shall include its own AS number in an b) the originating speaker shall include its own AS number in an
AS_CONFED_SEQUENCE segment of the AS_PATH attribute of all UPDATE AS_CONFED_SEQUENCE segment of the AS_PATH attribute of all
messages sent to BGP speakers located in neighboring autonomous UPDATE messages sent to BGP speakers located in neighboring
systems that are members of the local confederation. (In this autonomous systems that are members of the local confederation.
case, the AS number of the originating speaker's member autonomous (In this case, the AS number of the originating speaker's member
system number will be the only entry in the AS_PATH attribute). autonomous system number will be the only entry in the AS_PATH
attribute).
c) the originating speaker shall include its own confederation c) the originating speaker shall include its own confederation
identifier in a AS_SEQUENCE segment of the AS_PATH attribute of identifier in a AS_SEQUENCE segment of the AS_PATH attribute of
all UPDATE messages sent to BGP speakers located in neighboring all UPDATE messages sent to BGP speakers located in neighboring
autonomous systems that are not members of the local autonomous systems that are not members of the local
confederation. (In this case, the confederation identifier of the confederation. (In this case, the confederation identifier of
originating speaker's member confederation will be the only entry the originating speaker's member confederation will be the only
in the AS_PATH attribute). entry in the AS_PATH attribute).
Common Administration Issues Common Administration Issues
It is reasonable for member ASs of a confederation to share a common It is reasonable for member ASs of a confederation to share a common
administration and IGP information for the entire confederation. administration and IGP information for the entire confederation.
It shall be legal for a BGP speaker to advertise an unchanged It shall be legal for a BGP speaker to advertise an unchanged
NEXT_HOP and MULTI_EXIT_DISCRIMINATOR attribute to peers in a NEXT_HOP and MULTI_EXIT_DISCRIMINATOR attribute to peers in a
neighboring AS within the same confederation. In addition, the neighboring AS within the same confederation. In addition, the
restriction against sending the LOCAL_PREFERENCE attribute to peers restriction against sending the LOCAL_PREFERENCE attribute to peers
skipping to change at page 7, line 11 skipping to change at page 6, line 34
requirement that all BGP speakers participating in a confederation to requirement that all BGP speakers participating in a confederation to
allow the use of legacy units provided they have no external (i.e. allow the use of legacy units provided they have no external (i.e.
neither inter-AS nor intra-confederation) connectivity. neither inter-AS nor intra-confederation) connectivity.
At the time of this writing, an implementation of this extension as At the time of this writing, an implementation of this extension as
documented is widely deployed throughout the Internet, therefore the documented is widely deployed throughout the Internet, therefore the
value of any change that is incompatible with this document must be value of any change that is incompatible with this document must be
weighed against the benefit gained from a relaxation of this weighed against the benefit gained from a relaxation of this
restriction. restriction.
References
[1] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4 (BGP-4)",
RFC 1771, March 1995.
[2] Kunzinger, C. Editor, "Inter-Domain Routing Protocol", ISO/IEC
10747, October 1993.
Security Considerations Security Considerations
Security considerations are not discussed in this memo. Security issues are not discussed in this memo.
Acknowledgments Acknowledgments
Ravi Chandra and Yakov Rekhter reviewed this document and provided Ravi Chandra and Yakov Rekhter reviewed this document and provided
constructive and valuable comments. constructive and valuable comments.
Author's Address: Author's Address
Paul Traina Paul Traina
cisco Systems, Inc. cisco Systems, Inc.
170 W. Tasman Dr. 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
pst@cisco.com
References
[1] RFC1771
Rekhter, Y., and Li, T., "A Border Gateway Protocol 4 (BGP-4)", March
1995.
[2] ISO/IEC 10747 EMail: pst@cisco.com
Kunzinger, C. Editor, "Inter-Domain Routing Protocol", October 1993
 End of changes. 14 change blocks. 
53 lines changed or deleted 43 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/