思科网关冗余协议配置

1.VRRP技术

虚拟路由冗余协议(Virtual Router Redundancy Protocol，简称VRRP)，是一个IP协议族，我们知道IP协议族里面有ICMP、OSPF，VRRP也是IP协议族的一员，协议号为112。在VRRP里面，设备有两种角色Master,Backup），其中Master负责跑业务流量，而Backup负责备份，当Master挂掉之后，Backup自动抢占为Master，然后所有的数据从Master上走 。VRRP主要是用来做出口链路的冗余备份的，可以有多个网关设备加入一个备份组，但是只能有一个Master设备，当Master设备挂掉之后，其他的Backup设备自动抢占为Master设备，保障网络的可靠性。

2.VRRP配置实例

要求：
SW1为vlan10的主网关，vlan20的备份网关
SW2为vlan20的主网关，vlan10的备份网关

配置参数

VLAN10
SW1配置
interface Vlan10
 ip address 10.10.10.3 255.255.255.0
 vrrp 1 ip 10.10.10.1
 vrrp 1 preempt delay minimum 5
 vrrp 1 priority 120
 vrrp 1 track 1 decrement 20
!
SW2配置
interface Vlan10
 ip address 10.10.10.4 255.255.255.0
 vrrp 1 ip 10.10.10.1
 vrrp 1 preempt delay minimum 5
 vrrp 1 priority 150
!

VLAN20
SW1配置
interface Vlan20
 ip address 10.10.20.3 255.255.255.0
 vrrp 2 ip 10.10.20.1
 vrrp 2 preempt delay minimum 5
!
SW2配置
track 2 interface Ethernet0/2 line-protocol //追踪上联端口
interface Vlan20
 ip address 10.10.20.4 255.255.255.0
 vrrp 2 ip 10.10.20.1
 vrrp 2 preempt delay minimum 5
 vrrp 2 priority 120
 vrrp 2 track 2 decrement 40
!

结果测试：

在SW1上查看
Switch#show vrrp
Vlan10 - Group 1  
  State is Backup  
  Virtual IP address is 10.10.10.1
  Virtual MAC address is 0000.5e00.0101
  Advertisement interval is 1.000 sec
  Preemption enabled, delay min 5 secs
  Priority is 120 
    Track object 1 state Up decrement 20
  Master Router is 10.10.10.4, priority is 150 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.531 sec (expires in 3.431 sec)

Vlan20 - Group 2  
  State is Backup  
  Virtual IP address is 10.10.20.1
  Virtual MAC address is 0000.5e00.0102
  Advertisement interval is 1.000 sec
  Preemption enabled, delay min 5 secs
  Priority is 100 
  Master Router is 10.10.20.4, priority is 120 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.609 sec (expires in 2.994 sec)

在SW2上查看
Switch#show vrrp
Vlan10 - Group 1  
  State is Master  
  Virtual IP address is 10.10.10.1
  Virtual MAC address is 0000.5e00.0101
  Advertisement interval is 1.000 sec
  Preemption enabled, delay min 5 secs
  Priority is 150 
  Master Router is 10.10.10.4 (local), priority is 150 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.414 sec

Vlan20 - Group 2  
  State is Master  
  Virtual IP address is 10.10.20.1
  Virtual MAC address is 0000.5e00.0102
  Advertisement interval is 1.000 sec
  Preemption enabled, delay min 5 secs
  Priority is 120 
    Track object 2 state Up decrement 40
  Master Router is 10.10.20.4 (local), priority is 120 
  Master Advertisement interval is 1.000 sec
  Master Down interval is 3.531 sec

追踪测试：

关闭SW2的上联端口e0/2
SW1切换为VLAN20的主网关
Switch(config)#int e 0/2
Switch(config-if)#sh
Switch(config-if)#
*Nov 11 06:13:48.928: %TRACK-6-STATE: 2 interface Et0/2 line-protocol Up -> Down
Switch(config-if)#
*Nov 11 06:13:50.933: %LINK-5-CHANGED: Interface Ethernet0/2, changed state to administratively down
*Nov 11 06:13:51.935: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0/2, changed state to down
Switch(config-if)#
*Nov 11 06:13:54.461: %VRRP-6-STATECHANGE: Vl20 Grp 2 state Master -> Backup
SW2开启上联端口e0/2
SW2恢复为VLAN20的主网关
Switch(config-if)#no sh
Switch(config-if)#
*Nov 11 06:14:05.361: %LINK-3-UPDOWN: Interface Ethernet0/2, changed state to up
Switch(config-if)#
*Nov 11 06:14:06.699: %TRACK-6-STATE: 2 interface Et0/2 line-protocol Down -> Up
Switch(config-if)#
*Nov 11 06:14:07.373: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0/2, changed state to up
Switch(config-if)#
*Nov 11 06:14:12.035: %VRRP-6-STATECHANGE: Vl20 Grp 2 state Backup -> Master