Overview IS-IS

The IS-IS (Intermediate System to Intermediate System) is the IGP (Interior Gateway Protocol) based on the SPF algorithm. The basic design theory and algorithm for the IS-IS protocol are consistent with the OSPF. The IS-IS protocol is the routing protocol based on the link layer, which is irrelevant to the network layer (IPv4, IPv6, and OSI). It is not restricted by the network layer, and therefore it has good extensibility.

The IS-IS protocol can support the routing of multi-protocol stacks, including IPv4, IPv6, and OSI. The IS-IS protocol is initially applied to the OSI protocol stack (ISO10589) and then extended to the routing of IPv4 protocol stack (RFC1195) and IPv6 protocol stack (RFC5308).and, it can be further extended to support the CSPF calculation of the MPLS-TE (RFC3784).

The IS-IS protocol is characterized with good capability (inconsistent extended functions between devices can be compatible perfectly), large network capacity, able to support multi-protocol stacks, able to upgrade smoothly, unlikely to be faulty compared with the OSPF. Therefore, the IS-IS protocol applies to the large-size core backbone network. This section describes how to configure the IS-IS dynamic routing protocol on the device for network interconnection.