Operation Manual – Routing ProtocolH3C S7500 Series Ethernet Switches Chapter 5 IS-IS Configuration5-6For example, there is a NET named 47.0001.aaaa.bbbb.cccc.00, where:Area=47.0001, System ID=aaaa.bbbb.cccc, SEL=00.Here is another example. A NET named 01.1111.2222.4444.00 exists where:Area=01, System ID=1111.2222.4444, SEL=00.5.1.4 IS-IS PDU FormatDirectly encapsulated in data link layer frames, IS-IS packets fall into three categories:Hello, LSP, and SNP.I. HelloThe Hello packet is used by routers to establish and maintain the neighborrelationship. It is also called IS-to-IS Hello PDUs (IIH). For broadcast network, theLevel-1 router uses the Level-1 LAN IIH; and the Level-2 router uses the Level-2 LANIIH. The P2P IIH is used on point-to-point network. Point-to-Point IIH is used on anon-broadcast network.II. LSP packet formatThe link state PDUs (LSP) carry link state information. There are two types: Level-1LSP and Level-2 LSP. The Level-2 LSP is sent by the Level-2 router, and the Level-1LSP is sent by the Level-1 router. The level-1-2 router can sent both types of theLSPs.III. SNP formatThe sequence number PDUs (SNP) confirms the latest LSPs received by neighbors.It is similar to the Acknowledge packet, but more efficient.The SNP contains the complete SNP (CSNP) and the partial SNP (PSNP), which arefurther divided into Level-1 CSNP, Level-2 CSNP, Level-1 PSNP and Level-2 PSNP.PSNP only contains the sequence numbers of one or multiple latest received LSPs. Itcan acknowledge multiple LSPs at one time. When LSDBs are not synchronized, aPSNP is used to request new LSPs from neighbors.CSNP covers the summary of all LSPs in the LSDB to synchronize the LSDB betweenneighboring routers. On broadcast networks, CSNP is sent by the DIS periodically(10s by default). On point-to-point networks, CSNP is only sent during the firstadjacency establishment.5.2 IS-IS Configuration Task ListComplete the following tasks to configure IS-IS:
