BGP OSPF Interaction
RFC 1403
Document | Type |
RFC - Historic
(January 1993; No errata)
Obsoletes RFC 1364
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Authors | |||
Last updated | 2013-03-02 | ||
Stream | Legacy stream | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 1403 (Historic) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group K. Varadhan Request for Comments: 1403 OARnet Obsoletes: 1364 January 1993 BGP OSPF Interaction 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 memo defines the various criteria to be used when designing an Autonomous System Border Routers (ASBR) that will run BGP with other ASBRs external to the AS and OSPF as its IGP. This is a republication of RFC 1364 to correct some editorial problems. Table of Contents 1. Introduction .................................................... 2 2. Route Exchange .................................................. 3 2.1. Exporting OSPF routes into BGP ................................ 3 2.2. Importing BGP routes into OSPF ................................ 4 3. BGP Identifier and OSPF router ID ............................... 5 4. Setting OSPF tags, BGP ORIGIN and AS_PATH attributes ............ 6 4.1. Semantics of the characteristics bits ......................... 8 4.2. Configuration parameters for setting the OSPF tag ............. 9 4.3. Manually configured tags ...................................... 10 4.4. Automatically generated tags .................................. 10 4.4.1. Routes with incomplete path information, PathLength = 0 ..... 10 4.4.2. Routes with incomplete path information, PathLength = 1 ..... 11 4.4.3. Routes with incomplete path information, PathLength >= 1 .... 11 4.4.4. Routes with complete path information, PathLength = 0 ....... 12 4.4.5. Routes with complete path information, PathLength = 1 ....... 12 4.4.6. Routes with complete path information, PathLength >= 1 ...... 13 4.5. Miscellaneous tag settings .................................... 13 4.6. Summary of the TagType field setting .......................... 14 5. Setting OSPF Forwarding Address and BGP NEXT_HOP attribute ...... 14 6. Security Considerations ......................................... 15 7. Acknowledgements ................................................ 15 8. Bibliography .................................................... 16 9. Author's Address ................................................ 17 Varadhan [Page 1] RFC 1403 BGP OSPF Interaction January 1993 1. Introduction This document defines the various criteria to be used when designing an Autonomous System Border Routers (ASBR) that will run BGP [RFC1267] with other ASBRs external to the AS, and OSPF [RFC1247] as its IGP. This document defines how the following fields in OSPF and attributes in BGP are to be set when interfacing between BGP and OSPF at an ASBR: OSPF cost and type vs. BGP INTER-AS METRIC OSPF tag vs. BGP ORIGIN and AS_PATH OSPF Forwarding Address vs. BGP NEXT_HOP For a more general treatise on routing and route exchange problems, please refer to [ROUTE-LEAKING] and [NEXT-HOP] by Philip Almquist. This document uses the two terms "Autonomous System" and "Routing Domain". The definitions for the two are below: The term Autonomous System is the same as is used in the BGP-3 RFC [RFC1267], given below: "The use of the term Autonomous System here stresses the fact that, even when multiple IGPs and metrics are used, the administration of an AS appears to other ASs to have a single coherent interior routing plan and presents a consistent picture of what networks are reachable through it. From the standpoint of exterior routing, an AS can be viewed as monolithic: reachability to networks directly connected to the AS must be equivalent from all border gateways of the AS." The term Routing Domain was first used in [ROUTE-LEAKING] and is given below: "A Routing Domain is a collection of routers which coordinate their routing knowledge using a single (instance of) a routing protocol." This document follows the conventions embodied in the Host Requirements RFCs [RFC1122, RFC1123], when using the terms "MUST", "SHOULD", and "MAY" for the various requirements. Varadhan [Page 2] RFC 1403 BGP OSPF Interaction January 1993 2. Route Exchange This section discusses the constraints that must be met to exchange routes between an external BGP session with a peer from another ASShow full document text