VRRP（Virtual Router Redundancy Protocol，虚拟路由冗余协议）
VRRP Router角色（dis vrrp）
一.Master：主用
选择：1.优先级最高（可抢占）；2.IP最高（不可抢占）。
作用：1.用VMAC应答主机ARP请求；2.转发用户Data。
二.Backup：备用
监听Master定期（1秒）发送的通告，在Master_Down_Interval时间内未收到，则认为Master失效，立即成为Master，即切换。
SW1
syst
sysn SW1
vlan 2
int ether 0/0/1
port link-t trun
port trunk all vla all
int ether 0/0/2
port link-t trun
port trunk all vla all
int vlanif 2
ip add 192.168.20.5 24
ospf 1
ar 0
net 192.168.20.0 0.0.0.255
user-interf con 0
idle-t 0 0
qSW2
syst
sysn SW2
int ether 0/0/1
port link-t trun
port trunk all vla all
int ether 0/0/2
port link-t trun
port trunk all vla all
user-interf con 0
idle-t 0 0
qSWA
syst
sysn SWA
vlan 2
int g0/0/1
port link-t trun
port trunk all vla all
int g0/0/2
port link-t trun
port trunk all vla all
int vlanif 1
ip add 192.168.10.1 24
int vlanif 2
ip add 192.168.20.1 24
ospf 1
ar 0
net 192.168.10.0 0.0.0.255
net 192.168.20.0 0.0.0.255
user-interf con 0
idle-t 0 0
qSWB
syst
sysn SWB
vlan 2
int g0/0/1
port link-t trun
port trunk all vla all
int g0/0/2
port link-t trun
port trunk all vla all
int vlanif 1
ip add 192.168.10.2 24
int vlanif 2
ip add 192.168.20.2 24
ospf 1
ar 0
net 192.168.10.0 0.0.0.255
net 192.168.20.0 0.0.0.255
user-interf con 0
idle-t 0 0
qSWA
return
sys
stp priority 4096
int g0/0/3
port link-type trunk
port trunk allow-pass vlan all
int vlanif 1
vrrp vrid 1 virtual-ip 192.168.10.254
vrrp vrid 1 priority 110
dis vrrpSWB
return
sys
stp priority 8192
int g0/0/3
port link-type trunk
port trunk allow-pass vlan all
int vlanif 1
vrrp vrid 1 virtual-ip 192.168.10.254
dis vrrp验证测试
#CLIENT1
tracert 192.168.20.5
#SWA
return
sys
int vlanif 1
sh
#CLIENT1
tracert 192.168.20.5
#SWA
return
sys
int vlanif 1
undo sh
#CLIENT1
tracert 192.168.20.5接口跟踪（Track）功能，当上行链路（Uplink）down时，Master降低优先级（默认降低10），进行主备切换；当上行链路恢复up，原Master恢复优先级，抢占为Master，即回切。
SWA
sys
int vlanif 1
vrrp vrid 1 track int g0/0/2 redu 20
vrrp vrid 1 track int g0/0/3 redu 20
#关闭接口验证
int g0/0/2
sh
dis vrrp
#CLIENT1
tracert 192.168.20.5
#SWA开启接口验证是否恢复
sys
int g0/0/2
undo sh
dis vrrp
#CLIENT1
tracert 192.168.20.5