The present invention relates to a method and system for implementing link
level protocol redundancy in a router. In particular, the invention
relates to providing redundancy of the Intermediate System Intra-domain
Routing Information Exchange Protocol (IS-IS) routing protocol. An active
processor provides IS-IS operations. In the present invention, a standby
processor is coupled to the active processor. During the initial
synchronization, all protocol information from the active processor is
forwarded to the standby processor. The protocol information can include
IS-IS global protocol information, IS-IS configuration information, IS-IS
adjacencies information, IS-IS interface information and link state
packet information. Thereafter, any updates of protocol information are
immediately forwarded to the standby processor in an orderly and
controlled manner. Upon failure of the active processor, the router is
switched to the standby processor and all IS-IS protocol operations are
performed on what used to be the standby processor.