The Intermediate System to Intermediate System (IS-IS) protocol is a pure link-state protocol, similar to OSPF, and it is defined in RFC 1142. IS-IS is currently used mostly in very large service provider environments, as it lost the battle versus OSPF for Internet-wide supremacy. One thing to consider from a network design perspective is that many engineers are not knowledgeable about the IS-IS protocol.
IS-IS has many similarities to OSPF, such as it is a classless routing protocol, it uses VLSM, and it supports authentication. IS-IS also presents some key differences from OSPF . . .
The content below this message is for members only.