The Virtual Router Redundancy Protocol (VRRP) is a Redundancy protocol that dynamically assigns responsibility for one or more virtual routers to the VRRP routers on a LAN, allowing several routers on a multiaccess link to utilize the same virtual IP address. In a VRRP configuration, one router is elected as the virtual router master, with the other routers acting as backups in case the virtual router master fails.
Configuration for VRRP
Configuration on INBSW1 (Master)
INBSW1(config)#interface f0/0
INBSW1 (config-if)#ip address 192.168.1.2 255.255.255.0
INBSW1 (config-if)#no shutdown
INBSW1 (config-if)#vrrp 1 ip 192.168.1.1
INBSW1 (config-if)#vrrp 1 preempt
Configuration on INBSW2 (Backup)
INBSW2(config)#interface f0/0
INBSW2(config-if)#ip address 192.168.1.3 255.255.255.0
INBSW2(config-if)#no shutdown
INBSW2(config-if)#vrrp 1 ip 192.168.1.1
INBSW2config-if)#vrpp 1 priority 90
Configuration on INBSW3 (Backup)
INBSW3(config)#interface f0/0
INBSW3(config-if)#ip address 192.168.1.4 255.255.255.0
INBSW3(config-if)#no shutdown
INBSW3(config-if)#vrrp 1 ip 192.168.1.1
INBSW3config-if)#vrpp 1 priority 80
As per the above configuration, INBSW1 will be master Switch in VRRP group 1. When INBSW1 fails INBSW2 will take over as it has Higher priority between INBSW2 and INBSW3.
Preempt statement in the first switch is used to make sure it will take control as master when it came alive after fail.
Commands to Verify VRRP:
show vrrp [ interface type interface-path-id[vrid] ] [ brief | detail | statistics[all] ]
VRRP Command Syntax and details
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
| Step 1 | enable Example:Router> enable | Enables privileged EXEC mode.Enter your password if prompted. |
| Step 2 | configure terminal Example:Router# configure terminal | Enters global configuration mode. |
| Step 3 | interface type number Example:Router(config)# interface GigabitEthernet 0/0/0 | Enters interface configuration mode. |
| Step 4 | ip address ip-address mask Example:Router(config-if)# ip address 172.16.6.5 255.255.255.0 | Configures an IP address for an interface. |
| Step 5 | vrrp group description text Example:Router(config-if)# vrrp 10 description working-group | Assigns a text description to the VRRP group. |
| Step 6 | vrrp group priority level Example:Router(config-if)# vrrp 10 priority 110 | Sets the priority level of the router within a VRRP group.The default priority is 100. |
| Step 7 | vrrp group preempt [delay minimum seconds] Example:Router(config-if)# vrrp 10 preempt delay minimum 380 | Configures the router to take over as virtual router master for a VRRP group if it has a higher priority than the current virtual router master.The default delay period is 0 seconds.The router that is IP address owner will preempt, regardless of the setting of this command. |
| Step 8 | vrrp group timers advertise [sec] interval Example:Router(config-if)# vrrp 10 timers advertise 110 | Configures the interval between successive advertisements by the virtual router master in a VRRP group.The unit of the interval is in seconds unless the sec keyword is specified. The default interval value is 1 second.Note All routers in a VRRP group must use the same timer values. If the same timer values are not set, the routers in the VRRP group will not communicate with each other and any misconfigured router will change its state to master. |
| Step 9 | vrrp group timers learn Example:Router(config-if)# vrrp 10 timers learn | Configures the router, when it is acting as virtual router backup for a VRRP group, to learn the advertisement interval used by the virtual router master. |
| Step 10 | exit Example:Router(config-if)# exit | Exits interface configuration mode. |