Operation Manual – Routing ProtocolH3C S7500 Series Ethernet Switches Chapter 5 IS-IS Configuration5-1Chapter 5 IS-IS ConfigurationWhen configuring IS-IS, go to these sections for information you are interested in:z IS-IS Overviewz IS-IS Configuration Task Listz Displaying and Maintaining Integrated IS-IS Configurationz Integrated IS-IS Configuration Example5.1 IS-IS OverviewThe intermediate system-to-intermediate system (IS-IS) is a dynamic routing protocolstandardized by the International Organization for Standardization (ISO) to operate onconnectionless network protocol (CLNP).The IS-IS routing protocol has been adopted in RFC 1195 by the InternationalEngineer Task Force (IETF) to be applied in both TCP/IP and OSI reference models,and this form is called Integrated IS-IS or Dual IS-IS.The IS-IS routing protocol, based on the link state algorithm, is an interior gatewayprotocol (IGP) used within an Autonomous System. It is similar to open shortest pathfirst (OSPF) using shortest path first (SPF) algorithm to calculate best paths in thenetwork.5.1.1 Basic ConceptI. IS-IS terminologyz Intermediate system (IS). An IS, similar to a router in TCP/IP, is the basic unit inIS-IS protocol to generate and propagate routing information. In the following text,an IS equals to a router.z End system (ES). An ES refers to a host system in TCP/IP. ISO uses ES-ISprotocol to specify the communication between an ES and an IS, therefore an ESdoes not participate in the IS-IS process and can be ignored in the IS-IS protocol.z Routing domain (RD). A group of ISs exchange routing information with thesame routing protocol in a routing domain.z Area. An area is a division unit in a routing domain. The IS-IS protocol allows arouting domain to be divided into multiple areas.z Link state database (LSDB). All link states in the network consist of the LSDB.There is at least one LSDB in each IS. The IS uses SPF algorithm and LSDB togenerate its own routes.z Link state protocol data unit or link state packet (LSP). In the IS-IS routingprotocol, each IS can generate a LSP which contains all the link state information
