IS-IS is an interior gateway protocol, designed for use within an administrative domain or network. This is in contrast to exterior gateway protocols, primarily Border Gateway Protocol (BGP), which is used for routing between autonomous systems (RFC 1930).

TACACS+ provides Device Administration for routers, network access servers and other networked computing devices via one or more centralized servers. This document describes the protocol that is used by TACACS+.

"Jupiter Rising: A Decade of Clos Topologies and Centralized Control in Google’s Datacenter Network"