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发送1次hello包，1min超时（1min发送10个hello包）
sw2:
track 1 ip route 150.1.10.0 255.255.255.0 reachability-----跟踪目标可达
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---认证
standby track 1 decrement 31-----当跟踪的目标不可达，优先级减21
standby timers msec 100 msec 1000