RFC 1371 (rfc1371) - Page 2 of 9

Choosing a Common IGP for the IP Internet

RFC 1371                Choosing a "Common IGP"             October 1992


Table of Contents

   1. Background ....................................................  2
   2. Multiple Internet Standard Routing Protocols Possible .........  3
   3. A Common IGP ..................................................  3
   4. Impact of Multi-protocol Topology and Integrated IP/CLNP Routing 3
   5. Commitment to Both IP and CLNP ................................  5
   6. Some History ..................................................  5
   7. IESG Recommendations ..........................................  6
   7.1 Regarding the Common IGP for the IP Internet .................  6
   7.2 Regarding Integrated IP/CLNP Routing .........................  7
   7.3 Limits of the Common IGP Recommendation ......................  7
   8. References ....................................................  8
   9. Security Considerations .......................................  9
   10. Author's Address .............................................  9

1. Background

   There is a pressing need for a high functionality non-proprietary
   "common" Interior Gateway Protocol (IGP) for the TCP/IP protocol
   family.  An IGP is the routing protocol used within a single
   administrative domain (commonly referred to as an "Autonomous System"
   (AS).

   By "common", we simply mean a protocol that is ubiquitously available
   from all router vendors (as in "in common").  Users and network
   operators have expressed a strong need for routers from different
   vendors to have the capablity to interoperate within an AS through
   use of a common IGP.

   Note:  Routing between AS's is handled by a different type of routing
   protocol, called an "Exterior Gateway Protocol" ("an EGP", of which
   the Border Gateway Protocol [2] and "The Exterior Gateway Protocol"
   [3] are examples.)  The issues of routing between AS's using "an" EGP
   is not considered in this memo.

   There are two IGPs in the Internet standards track capable of routing
   IP traffic -- Open Shortest Path First (OSPF) [4] and Integrated IS-
   IS [5] (based on the OSI IS-IS). These two protocols are both modern
   "link state" routing protocols, based on the Dijkstra algorithm.
   There has been substantial interaction and cooperation among the
   engineers involved in each effort, and the protocols share some
   similar features.

   However, there are a number of technical design differences.  Most
   noteably, OSPF has been designed solely for support of the Internet
   Protocol (IP), while Integrated IS-IS has been designed to support
   both IP and the OSI Connectionless Network Layer Protocol (CLNP)



IESG