The Integrated IS-IS protocol was specified by Digital Equipment in 1990 under RFC 1195. In order to perform IP communications, some information was added to the IS-IS frame. However, the integration achieved comes at the expense of option capabilities in OSPF. OSPF increases the performance and functionality of TCP/IP networks quite considerably compared to Routing Information Protocol( RIP), but it still does not provide OSI compatibility and functionality.
The goal of Integrated IS-IS is clearly to migrate TCP/IP to Open Systems Interconnection (OSI).