350 CHAPTER 32: I NTEGRATED IS-IS CONFIGURATIONConfiguring IS-IS Timers Setting the Hello packet broadcast intervalThe IS-IS periodically sends the Hello packets from the interface and the routersmaintain the adjacency through the transmitting/receiving of the Hello packetsThe Hello packet interval can be modified.Perform the following configuration in interface view.Usually, two types of Hello packets are transported over a broadcast link: Level-1and Level-2 Hello packets. For different packets, different broadcast intervalsshould be set. However, there are two exceptions. One is when there is no levelseparation in the link, parameters of Level-1 and Level-2 need not be specified inthe command (adopt the default values). So the system will set the broadcastintervals of all packets as that of the level-1 Hello packet. The other is if Hellopackets are not separated according to level-1 and level-2 on the p2p links, theattribute of the packets need not be set either.By default, Hello packets are transmitted on an interface every 10 seconds.This command specifies to send Hello packets of the corresponding levels in theFast Hello mode (by setting the minimum value of Hello interval to 1 second). Ifthe number of packets is not specified in the related command, three Hellopackets will be sent per second.Perform the following configuration in interface view.If neither level-1 nor level-2 is specified, the default setting is Level-1 and Level-2Hello interval. Namely, the command works on both Level-1 and Level-2.Setting the CSNP packet broadcast intervalThe CSNP packet is transmitted by the DIS over the broadcast network tosynchronize the link state database (LSDB). The CSNP packet is regularly broadcastover the broadcast network at an interval, which can be set by users.Perform the following configuration in interface view.Table 323 Set the Hello packet broadcast intervalOperation CommandSet Hello packet interval, measured inseconds. isis timer hello seconds [ level-1 | level-2 ]Restore the default Hello packet interval onthe interface undo isis timer hello [ level-1 | level-2 ]Table 324 Configure to send Hello packets of the corresponding levels in the Fast HellomodeOperation CommandConfigure to send Hello packets of thecorresponding levels in the Fast Hello mode isis timer hello minimal [ level-1 | level-2 ]Restore the default value of Hello interval inthe Fast Hello mode.undo isis timer hello minimal [ level-1 |level-2 ]
