ISIS is the link-state routing protocol of choice in the OSI suite. Though the OSI protocol suite never came to be at a global internet scale, it does hold some interesting contrasts when compared to the TCP/IP protocol suite that we're all very much accustomed to. In summary, the key features of the OSI suite are:
- Multi-domain, multi-area, multi-level addressing, with variable length addressing fields, but fixed hierarchy
- Node-based addressing rather than interface-based addressing
Despite the difference in underlying the transport protocol suite, ISIS found popularity on large-scale service-provider networks during the years that the IETF were still standardising OSPF. Today, it is a first-class link-state routing protocol ...