Cisco Blog: HSRP vs. VRRP vs. GLBP
This last week, I ended up doing a basic deployment over at the AT&T NOC here in Mesa, Arizona. There's nothing like the feeling of walking into a NOC, complete with full hand scanners that also check for a pulse equipping each door, hundreds of racks of equipment, the fan whir so loud that you can't hear yourself think. Ah, I'm slipping back into it just thinking about it.
Back to the topic at hand: the client had dual routers connected to AT&T in the configuration below:
This redundant topology just begged to use one of the redundancy protocols: HSRP, VRRP, or GLBP. The big question is...which one? ...and why? Well, me being a Cisco spud, I immediately gravitated to HSRP since that's all I know very well. But before I left, I decided to check out the competition, here's what I found:
Cisco Hot-Standby Router Protocol (HSRP):
- Created by Cisco, for Cisco in 1994
- Uses a default hello timer of 3 seconds with a hold timer of 10 seconds
Virtual Router Redundancy Protocol (VRRP)
- Created by the IETF in 1999
- Works between multiple vendors
- Has faster timers than HSRP by default - hello of 1 second, hold timer of 3 seconds
Gateway Load Balancing Protocol (GLBP)
- Created by Cisco, for Cisco in 2005
- Identical features to HSRP, but allows an active-active connection that adds load-balancing features
Since this client had no need for load balancing, I decided to go with the VRRP option. The configuration was a piece of cake:
Router1(config-if)#vrrp 1 ip 10.1.6.1 (they obviously used a real IP address)
Router1(config-if)#vrrp 1 preempt
Router1(config-if)#vrrp 1 priority 100
Router2(config-if)#vrrp 1 ip 10.1.6.1
Router2(config-if)#vrrp 1 preempt
Router2(config-if)#vrrp 1 priority 120
This is what the end topology looked like. Obviously, I've removed the IP addresses to protect the innocent :).
I've also included links to the full Cisco documentation for each of these protocols.
