From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc1397.txt | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 doc/rfc/rfc1397.txt (limited to 'doc/rfc/rfc1397.txt') diff --git a/doc/rfc/rfc1397.txt b/doc/rfc/rfc1397.txt new file mode 100644 index 0000000..588f15f --- /dev/null +++ b/doc/rfc/rfc1397.txt @@ -0,0 +1,115 @@ + + + + + + +Network Working Group D. Haskin +Request for Comments: 1397 Bolt Beranek and Newman, Inc. + January 1993 + + + Default Route Advertisement In + BGP2 And BGP3 Versions Of The Border Gateway Protocol + +Status of this Memo + + This RFC specifies an IAB standards track protocol for the Internet + community, and requests discussion and suggestions for improvements. + Please refer to the current edition of the "IAB Official Protocol + Standards" for the standardization state and status of this protocol. + Distribution of this memo is unlimited. + +Abstract + + This document specifies the recommendation of the BGP Working Group + on default route advertisement support in BGP2 [1] and BGP3 [2] + versions of the Border Gateway Protocol. + + This recommendation only applies to BGP2 and BGP3 versions of the + Border Gateway Protocol since starting with the BGP4 [3] version a + default route advertisement capability is built in the protocol. + +1. Overview + + The purpose of the default route advertisement capability is to + advertise the IP address of a border gateway which can be used as the + default next hop to destinations that are not listed explicitly in + the BGP peer's routing table. + + This capability will allow routers, that are unable to maintain a + complete routing table (e.g., due to its size) to learn a border + gateway that is ready to handle the default traffic. Also, in + contrast to static defaults, if there is more than one default + gateway, this would make it possible for a BGP speaker to express a + preference for one over the other. It also reduces the need to + configure default routes in routers. + +2. Default Route Advertisement + + A default route is advertised in an UPDATE message that carries + reachability information for network 0.0.0.0. A Network field of + such an UPDATE message must contain the IP address 0.0.0.0 as the + indication that it carries a default route. The NEXT_HOP path + attribute of such a message provides the IP address of a border + + + +Haskin [Page 1] + +RFC 1397 Default Routes in Old BGPs January 1993 + + + gateway that can be used as a default next hop to destinations that + are not listed in the BGP peer's routing table. The value of the + ORIGIN attribute should be 2 (INCOMPLETE). The AS_PATH attribute + should be constructed according to the same rules that apply to a + conventional network advertisement. + + If multiple default routes are advertised by a BGP speaker, the + INTER-AS-METRIC path attribute can be included in the corresponding + UPDATE messages to express preference levels for entry points to the + same AS. + + The UNREACHABLE path attribute is used to indicate that a previously + advertised default route has become unreachable. + + UPDATE messages containing the default route advertisements should be + handled according to the rules that apply to all other UPDATE + messages. If multiple default route are acquired by a BGP speaker, a + route is selected according to the local policies adopted by this BGP + speaker. + +References + + [1] Lougheed, K., and Y. Rekhter, "A Border Gateway Protocol (BGP)", + RFC 1163, cisco Systems, T.J. Watson Research Center, IBM Corp., + June 1990. + + [2] Lougheed, K., and Y. Rekhter, "A Border Gateway Protocol 3 (BGP- + 3)", RFC 1267, cisco Systems, T.J. Watson Research Center, IBM + Corp., October 1991. + + [3] Rekhter, Y., and T. Li, "A Border Gateway Protocol 4 (BGP-4)", + Work in Progress, T.J. Watson Research Center, IBM Corp., cisco + Systems, December 1992. + +Security Considerations + + Security issues are not discussed in this memo. + +Author's Address + + Dimitry Haskin + Bolt, Beranek & Newman + 150 Cambridge Park Drive + Cambridge, MA 02140 + + Phone: 617-873-8609 + Email: dhaskin@bbn.com + + + + +Haskin [Page 2] + \ No newline at end of file -- cgit v1.2.3