This RFC specifies an integrated routing protocol@ based on the OSI Intra-Domain IS-IS Routing Protocol@ which may be used as an interior gateway protocol (IGP) to support TCP/IP as well as OSI. This allows a single routing protocol to be used to support pure IP environments@ pure OSI environments@ and dual environments. This specification was developed by the IS-IS working group of the Internet Engineering Task Force. The OSI IS-IS protocol has reached a mature state@ and is ready for implementation and operational use. The most recent version of the OSI IS-IS protocol is contained in ISO DP 10589. The proposed standard for using IS-IS for support of TCP/IP will therefore make use of this version (with a minor bug correction@ as discussed in Annex B). We expect that future versions of this proposed standard will upgrade to the final International Standard version of IS-IS when available.