SW2:
vpc domain x
role priority 1
system-priority 2500
peer-keepalive destination sw3_ip source sw2_ip
int f0/3 f0/4
channel-group 20 mode active
no shutdown
int port-channel 20
switchport mode trunk
vpc peer-link
SW3:
vpc domain x
role priority 2
system-priority 2500
peer-keepalive destination sw2_ip source sw3_ip
int f0/3 f0/4
channel-group 20 mode active
no shutdown
int port-channel 20
switchport mode trunk
vpc peer-link
SW1:
int f0/1 f0/2
channel-group 30 mode active
inter port-channel 30
switchport mode trunk
查看VPC：show vpc
vpc类似华为M-LAG，非抢占，但在主设备宕机后，备设备可以成为主设备。反之，依然。
vpc的优先级是范围是从1到65636，并且缺省值是32667，越小越优。
vpc想对于堆叠更加利于设备升级。