On a VPN-supporting device, you can associate multiple VPN instances with multiple IS-IS processes to implement IS-IS multi-instance. IS-IS multi-process allows you to create multiple IS-IS processes in the same VPN (or on the public network). These IS-IS processes are independent of each other. Route exchange between IS-IS processes is similar to route exchange between routing protocols.
Each IS-IS process can be bound to a specified VPN instance. A typical application is as follows: In a VPN, IS-IS runs between PEs and CEs and also runs on the VPN backbone network. On the PEs, the two IS-IS processes are independent of each other.
IS-IS multi-processes share an RM routing table. IS-IS multi-instances use the RM routing tables in VPNs, and each VPN has its own RM routing table.
IS-IS multi-process allows a set of interfaces to be associated with a specified IS-IS process. This ensures that the specified IS-IS process performs all the protocol operations only on this set of interfaces. In this manner, multiple IS-IS processes can work on a single router and each process is responsible for managing a unique set of interfaces.
When creating an IS-IS process, you can bind it to a VPN instance to associate the IS-IS process with the VPN instance. The IS-IS process accepts and processes only the events related to the VPN instance. When the bound VPN instance is deleted, the IS-IS process is also deleted.