Following on from Part 1 HSRP of this 3 part mini blog post series the next topic is VRRP
The Virtual Router Redundancy Protocol (VRRP) eliminates the single point of failure inherent in the static default routed environment. VRRP specifies an election protocol that dynamically assigns responsibility for a virtual router it is described fully in RFC 5798
- Routers are Master & Backup instead of Primary and Standby as in HSRP.
- It is Preemptive by default
- Virtual MAC is 0000.5E00.01XX (XX represents the group number)
Configuration is done at the interface level with the vrrp command.
For the lab setup we will be using the same simple topology
To configure VRRP it is much the same as HSRP, just replacing the standby command for the vrrp command
As VRRP is preemptive by default you can see that when I increased the priority from 100 to 110 that R1 became the master
R1(config-if)#vrrp 1 ip 192.168.1.254 R1(config-if)# *Mar 1 00:05:11.099: %VRRP-6-STATECHANGE: Fa0/0 Grp 1 state Init -> Backup R1(config-if)#vrrp 1 ? authentication Authentication description Group specific description ip Enable Virtual Router Redundancy Protocol (VRRP) for IP preempt Enable preemption of lower priority Master priority Priority of this VRRP group shutdown Disable VRRP Configuration timers Set the VRRP timers track Event Tracking R1(config-if)#vrrp 1 priority ? <1-254> Priority level R1(config-if)#vrrp 1 priority 110 R1(config-if)# *Mar 1 00:05:34.263: %VRRP-6-STATECHANGE: Fa0/0 Grp 1 state Backup -> Master R1(config-if)#
By issuing the sh vrrp command you can see that the timers are a bit more aggressive with 1 second advertisement interval and a 4 second down interval.
R1#sh vrrp FastEthernet0/0 - Group 1 State is Master Virtual IP address is 192.168.1.254 Virtual MAC address is 0000.5e00.0101 Advertisement interval is 1.000 sec Preemption enabled Priority is 110 Master Router is 192.168.1.1 (local), p Master Advertisement interval is 1.000 Master Down interval is 3.570 sec R1#
If you want to explore VRRP further the Cisco Documentation can be found here:
To locate it on the Doc CD it is under IPFirst Hop Redundancy Protocols Configuration Guide, Cisco IOS Release 12.4T