3com DUA1750-2BAA01 Manual De Usuario

3Com Switch 8800 Configuration Guide 

Chapter 20  Integrated IS-IS Configuration

 

20-1 

Intermediate System-to-Intermediate System (IS-IS) intra-domain routing information 

exchange protocol is designed by the international organization for standardization 

(ISO) for connection-less network protocol (CLNP). This protocol is a dynamic routing 

protocol. To let this protocol support IP routing, IETF expands and modifies IS-IS in 

RFC1195, applying the protocol to TCP/IP and OSI. The modified IS-IS is called 

Integrated IS-IS or Dual IS-IS. 

IS-IS is a link state protocol, which uses shortest path first (SPF) algorithm. IS-IS and 

the OSPF protocol are similar in many aspects. As an interior gateway protocol (IGP), 

IS-IS is applied inside an AS. 

z 

Intermediate System (IS). IS equals a router of TCP/IP. It is the basic unit in IS-IS 

protocol used for propagating routing information and generating routes. In the 

following text, the IS shares the same meaning with the router. 

z 

End System (ES). It equals the host system of TCP/IP. ES does not process the 

IS-IS routing protocol, and therefore it can be ignored in the IS-IS protocol.  

z 

Routing Domain (RD). A group of ISs exchange routing information with the same 

routing protocol in a routing domain. 

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Area. Area is the division unit in the routing domain.  

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Link State DataBase (LSDB). All the link states in the network form the LSDB. In 

an IS, at least one LSDB is available. The IS uses the SPF algorithm and the 

LSDB to generate its own routes. 

z 

Link State Protocol Data Unit (LSPDU). In the IS-IS, each IS will generate an LSP 

which contains all the link state information of the IS. Each IS collects all the LSPs 

in the local area to generate its own LSDB. 

z 

Network Protocol Data Unit (NPDU). It is the network layer packets of OSI and 

equals the IP packet of TCP/IP.  

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Designated IS (DIS). It is the elected router on the broadcast network. 

z 

Network Service Access Point (NSAP) is the network layer address of OSI. It 

identifies an abstract network service access point and describes the very network 

address structure for the OSI model.