客户需求：客户HostA通过Switch双归属到SwitchA和SwitchB。
为保证用户的各种业务在网络传输中不中断，需在SwitchA和SwitchB上配置VRRP主备备份功能。正常情况下，主机以SwitchA为默认网关接入Internet，当SwitchA故障时，SwitchB接替SwitchA作为网关继续进行工作，实现网关的冗余备份。SwitchA故障恢复后，其延时20秒通过抢占的方式重新成为Master，承担数据传输。
需要注意的是：确保该场景下互联接口的STP处于未使能状态。同时将互连接口退出VLAN1，避免形成环路。因为在使能STP的环形网络中，如果用交换机的VLANIF接口构建三层网络，会导致某个端口被阻塞，从而导致三层业务不能正常运行。
配置VRRP主备备份组网图
配置思路：采用VRRP主备备份实现网关冗余备份，配置思路如下：
配置各设备接口IP地址及路由协议，使各设备间网络层连通。
在SwitchA和SwitchB上配置VRRP备份组。其中，SwitchA上配置较高优先级和20秒抢占延时，作为Master设备承担流量转发；SwitchB上配置较低优先级，作为备用交换机，实现网关冗余备份。
操作步骤
配置设备间的网络互连
# 配置设备各接口的IP地址，以SwitchA为例。SwitchB和SwitchC的配置与SwitchA类似，详见下文配置文件。
<HUAWEI> system-view
[HUAWEI] sysname SwitchA
[SwitchA] vlan batch 100 300
[SwitchA] interface gigabitethernet 1/0/1
[SwitchA-GigabitEthernet1/0/1] port link-type hybrid
[SwitchA-GigabitEthernet1/0/1] port hybrid pvid vlan 300
[SwitchA-GigabitEthernet1/0/1] port hybrid untagged vlan 300
[SwitchA-GigabitEthernet1/0/1] quit
[SwitchA] interface gigabitethernet 1/0/2
[SwitchA-GigabitEthernet1/0/2] port link-type hybrid
[SwitchA-GigabitEthernet1/0/2] port hybrid pvid vlan 100
[SwitchA-GigabitEthernet1/0/2] port hybrid untagged vlan 100
[SwitchA-GigabitEthernet1/0/2] quit
[SwitchA] interface vlanif 100
[SwitchA-Vlanif100] ip address 10.1.1.1 24
[SwitchA-Vlanif100] quit
[SwitchA] interface vlanif 300
[SwitchA-Vlanif300] ip address 192.168.1.1 24
[SwitchA-Vlanif300] quit
# 配置Switch的二层转发功能。
<HUAWEI> system-view
[HUAWEI] sysname Switch
[Switch] vlan 100
[Switch-vlan100] quit
[Switch] interface gigabitethernet 1/0/1
[Switch-GigabitEthernet1/0/1] port link-type hybrid
[Switch-GigabitEthernet1/0/1] port hybrid pvid vlan 100
[Switch-GigabitEthernet1/0/1] port hybrid untagged vlan 100
[Switch-GigabitEthernet1/0/1] quit
[Switch] interface gigabitethernet 1/0/2
[Switch-GigabitEthernet1/0/2] port link-type hybrid
[Switch-GigabitEthernet1/0/2] port hybrid pvid vlan 100
[Switch-GigabitEthernet1/0/2] port hybrid untagged vlan 100
[Switch-GigabitEthernet1/0/2] quit
# 配置SwitchA、SwitchB和SwitchC间采用OSPF协议进行互连。以SwitchA为例，SwitchB和SwitchC的配置与SwitchA类似，详见配置文件。
[SwitchA] ospf 1
[SwitchA-ospf-1] area 0
[SwitchA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[SwitchA-ospf-1-area-0.0.0.0] quit
[SwitchA-ospf-1] quit
配置VRRP备份组
# 在SwitchA上创建VRRP备份组1，配置SwitchA在该备份组中的优先级为120，并配置抢占时间为20秒。
[SwitchA] interface vlanif 100
[SwitchA-Vlanif100] vrrp vrid 1 virtual-ip 10.1.1.111
[SwitchA-Vlanif100] vrrp vrid 1 priority 120 //设备在VRRP备份组中的优先级缺省为100，修改Master设备的优先级大于Backup设备
[SwitchA-Vlanif100] vrrp vrid 1 preempt-mode timer delay 20 //设备在VRRP备份组中缺省采用立即抢占方式。修改Master设备的延迟抢占时间，以避免在网络环境不稳定时，由于双方频繁抢占而导致流量中断的问题
[SwitchA-Vlanif100] quit
# 在SwitchB上创建VRRP备份组1，其在该备份组中的优先级采用缺省值100（不需要配置）。
[SwitchB] interface vlanif 100
[SwitchB-Vlanif100] vrrp vrid 1 virtual-ip 10.1.1.111
[SwitchB-Vlanif100] quit
验证配置结果
# 完成上述配置以后，在SwitchA和SwitchB上分别执行display vrrp命令，可以看到SwitchA在备份组中的状态为Master，SwitchB在备份组中的状态为Backup。
[SwitchA] display vrrp
Vlanif100 | Virtual Router 1
State : Master
Virtual IP : 10.1.1.111
Master IP : 10.1.1.1
PriorityRun : 120
PriorityConfig : 120
MasterPriority : 120
Preempt : YES Delay Time : 20 s
TimerRun : 1 s
TimerConfig : 1 s
Auth type : NONE
Virtual MAC : 0000-5e00-0101
Check TTL : YES
Config type : normal-vrrp
Backup-forward : disabled
Create time : 2012-01-12 20:15:46
Last change time : 2012-01-12 20:15:46
[SwitchB] display vrrp
Vlanif100 | Virtual Router 1
State : Backup
Virtual IP : 10.1.1.111
Master IP : 10.1.1.1
PriorityRun : 100
PriorityConfig : 100
MasterPriority : 120
Preempt : YES Delay Time : 0 s
TimerRun : 1 s
TimerConfig : 1 s
Auth type : NONE
Virtual MAC : 0000-5e00-0101
Check TTL : YES
Config type : normal-vrrp
Backup-forward : disabled
Create time : 2012-01-12 20:15:46
Last change time : 2012-01-12 20:15:46
# 在SwitchA和SwitchB上执行display ip routing-table命令，SwitchA上可以看到路由表中有一条目的地址为虚拟IP地址的直连路由，而SwitchB上该路由为OSPF路由。SwitchA和SwitchB上的显示信息如下。
[SwitchA] display ip routing-table
Route Flags: R - relay, D - download to fib, T - to vpn-instance
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 9 Routes : 10
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.1.1.0/24 Direct 0 0 D 10.1.1.1 Vlanif100
10.1.1.1/32 Direct 0 0 D 127.0.0.1 Vlanif100
10.1.1.111/32 Direct 0 0 D 127.0.0.1 Vlanif100
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
172.16.1.0/24 OSPF 10 2 D 192.168.1.2 Vlanif300
192.168.1.0/24 Direct 0 0 D 192.168.1.1 Vlanif300
192.168.1.1/32 Direct 0 0 D 127.0.0.1 Vlanif300
192.168.2.0/24 OSPF 10 2 D 10.1.1.2 Vlanif100
OSPF 10 2 D 192.168.1.2 Vlanif300
[SwitchB] display ip routing-table
Route Flags: R - relay, D - download to fib, T - to vpn-instance
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 9 Routes : 10
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.1.1.0/24 Direct 0 0 D 10.1.1.2 Vlanif100
10.1.1.2/32 Direct 0 0 D 127.0.0.1 Vlanif100
10.1.1.111/32 OSPF 10 2 D 10.1.1.1 Vlanif100
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
172.16.1.0/24 OSPF 10 2 D 192.168.2.2 Vlanif200
192.168.1.0/24 OSPF 10 2 D 10.1.1.1 Vlanif100
OSPF 10 2 D 192.168.2.2 Vlanif200
192.168.2.0/24 Direct 0 0 D 192.168.2.1 Vlanif200
192.168.2.1/32 Direct 0 0 D 127.0.0.1 Vlanif200
# 在SwitchA的接口GE1/0/2上执行shutdown命令，模拟SwitchA出现故障。
[SwitchA] interface gigabitethernet 1/0/2
[SwitchA-GigabitEthernet1/0/2] shutdown
[SwitchA-GigabitEthernet1/0/2] quit
# 在SwitchB上执行display vrrp命令查看VRRP状态信息，可以看到SwitchB的状态是Master。
[SwitchB] display vrrp
Vlanif100 | Virtual Router 1
State : Master
Virtual IP : 10.1.1.111
Master IP : 10.1.1.2
PriorityRun : 100
PriorityConfig : 100
MasterPriority : 100
Preempt : YES Delay Time : 0 s
TimerRun : 1 s
TimerConfig : 1 s
Auth type : NONE
Virtual MAC : 0000-5e00-0101
Check TTL : YES
Config type : normal-vrrp
Backup-forward : disabled
Create time : 2012-01-12 20:15:46
Last change time : 2012-01-12 20:18:40
# 在SwitchA的接口GE1/0/2上执行undo shutdown命令。
[SwitchA] interface gigabitethernet 1/0/2
[SwitchA-GigabitEthernet1/0/2] undo shutdown
[SwitchA-GigabitEthernet1/0/2] quit
# 等待20秒后，在SwitchA上执行display vrrp命令查看VRRP状态信息，可以看到SwitchA的状态恢复成Master。
[SwitchA] display vrrp
Vlanif100 | Virtual Router 1
State : Master
Virtual IP : 10.1.1.111
Master IP : 10.1.1.1
PriorityRun : 120
PriorityConfig : 120
MasterPriority : 120
Preempt : YES Delay Time : 20 s
TimerRun : 1 s
TimerConfig : 1 s
Auth type : NONE
Virtual MAC : 0000-5e00-0101
Check TTL : YES
Config type : normal-vrrp
Backup-forward : disabled
Create time : 2012-01-12 20:15:46
Last change time : 2012-01-12 20:20:56
配置文件
SwitchA的配置文件
#
sysname SwitchA
#
vlan batch 100 300
#
interface Vlanif100
ip address 10.1.1.1 255.255.255.0
vrrp vrid 1 virtual-ip 10.1.1.111
vrrp vrid 1 priority 120
vrrp vrid 1 preempt-mode timer delay 20
#
interface Vlanif300
ip address 192.168.1.1 255.255.255.0
#
interface GigabitEthernet1/0/1
port link-type hybrid
port hybrid pvid vlan 300
port hybrid untagged vlan 300
#
interface GigabitEthernet1/0/2
port link-type hybrid
port hybrid pvid vlan 100
port hybrid untagged vlan 100
#
ospf 1
area 0.0.0.0
network 10.1.1.0 0.0.0.255
network 192.168.1.0 0.0.0.255
#
return
SwitchB的配置文件
#
sysname SwitchB
#
vlan batch 100 200
#
interface Vlanif100
ip address 10.1.1.2 255.255.255.0
vrrp vrid 1 virtual-ip 10.1.1.111
#
interface Vlanif200
ip address 192.168.2.1 255.255.255.0
#
interface GigabitEthernet1/0/1
port link-type hybrid
port hybrid pvid vlan 200
port hybrid untagged vlan 200
#
interface GigabitEthernet1/0/2
port link-type hybrid
port hybrid pvid vlan 100
port hybrid untagged vlan 100
#
ospf 1
area 0.0.0.0
network 10.1.1.0 0.0.0.255
network 192.168.2.0 0.0.0.255
#
return
SwitchC的配置文件
#
sysname SwitchC
#
vlan batch 200 300 400
#
interface Vlanif200
ip address 192.168.2.2 255.255.255.0
#
interface Vlanif300
ip address 192.168.1.2 255.255.255.0
#
interface Vlanif400
ip address 172.16.1.1 255.255.255.0
#
interface GigabitEthernet1/0/1
port link-type hybrid
port hybrid pvid vlan 300
port hybrid untagged vlan 300
#
interface GigabitEthernet1/0/2
port link-type hybrid
port hybrid pvid vlan 200
port hybrid untagged vlan 200
#
interface GigabitEthernet1/0/3
port link-type hybrid
port hybrid pvid vlan 400
port hybrid untagged vlan 400
#
ospf 1
area 0.0.0.0
network 172.16.1.0 0.0.0.255
network 192.168.1.0 0.0.0.255
network 192.168.2.0 0.0.0.255
#
return
Switch的配置文件
#
sysname Switch
#
vlan batch 100
#
interface GigabitEthernet1/0/1
port link-type hybrid
port hybrid pvid vlan 100
port hybrid untagged vlan 100
#
interface GigabitEthernet1/0/2
port link-type hybrid
port hybrid pvid vlan 100
port hybrid untagged vlan 100
#
return
