Editing IS-IS (section)

== Description ==
IS-IS is an [[interior gateway protocol]], designed for use within an [[administrative domain]] or network.  This is in contrast to [[exterior gateway protocol]]s, primarily [[Border Gateway Protocol]] (BGP), which is used for routing between [[autonomous system (internet)|autonomous systems]].{{Ref RFC|1930}}

IS-IS is a [[link-state routing protocol]], operating by reliably flooding link state information throughout a network of [[router (networking)|routers]]. Each IS-IS router independently builds a database of the network's topology, aggregating the flooded network information.  Like the [[Open Shortest Path First|OSPF]] protocol, IS-IS uses [[Dijkstra's algorithm]] for computing the best path through the network.  Packets ([[datagram]]s) are then forwarded, based on the computed ideal path, through the network to the destination.