sw1:
inter vlan 5
ip add 10.10.100.2 255.255.255.0
no shut
standby ip 10.10.100.254
standby preenpt
standby authentication md5 key-string ccnp
standby timers msec 100 1-----200msec發送1次hello包，1min超時（1min發送10個hello包）
sw2:
track 1 ip route 150.1.10.0 255.255.255.0 reachability-----跟蹤目標可達
inter vlan 5
ip add 10.10.100.1 255.255.255.0
no shut
standby ip 10.10.100.254
standby priority 130
standby preempt
standby authentication md5 key-string ccnp---認證
standby track 1 decrement 31-----當跟蹤的目標不可達，優先級減21
standby timers msec 100 msec 1000