Intermediate System-to-Intermediate System (IS-IS) is a link state routing protocol that is part of the OSI family of protocols. Like OSPF, it uses Dijkstra’s SPF algorithm to choose routes. IS-IS is a classless interior gateway protocol that uses router resources efficiently and scales to large networks, such as large Internet service providers (ISP).
Table 4-1 lists some IS-IS terms, acronyms, and their meanings.
Table 4-1. IS-IS Acronyms
Identifies a physical interface on the router.
Complete Sequence Number PDU
A summary of a router’s complete LSDB.
Connectionless Network Protocol
OSI protocol used to provide the connectionless services.
Connectionless Network Services
OSI data delivery service ...