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April 15, 2006
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.
Cisco HSRP
Cisco GLBP
IETF VRRP
Posted by JC at April 15, 2006 6:47 PM
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Comments
There are a few more differences between HSRP and VRRP... In VRRP the standby speaker doesn't send out hellos, while they do in HSRP. Threw me for a loop the first time I ran into it (Nokia IPSO hardware). I'm not so sure it's supported on all the hardware that HSRP is, either.
Sean
Posted by: Sean at April 15, 2006 7:53 PM
Wow - that's one I didn't know! When I was testing this with AT&T, I also found out that if the VRRP failover occurs, the IP address of the VRRP group is not ping-able. You can still ping THROUGH the VRRP connection, but just not TO the VRRP IP address. Only if the active router is active will the VRRP group IP address be ping-able. I haven't quite figured out why that is yet...Any ideas?
Posted by: Jeremy at April 17, 2006 11:13 AM
Under IPSO it's a setting under VRRP configuration, though I don't recall any differentiation between the primary and a backup... You just tell each individual node whether or not it will respond to requests on the VRRP address. I took a look through the 12.4 docs for VRRP and didn't see anything. Are you sure it wasn't an L2 problem?
Sean
Posted by: Sean at April 17, 2006 12:25 PM
If I setup HSRP between 2 routers with a virtual IP shared between them on say the LAN side, would I need to set this up on the WAN side also? This refers to an ISP I used to work for but still help every now and then. They have a multi-link frame relay connection provided/owned by Sprint w/2800 router, ge uplinks into 3640 fe0/0 port owned by ISP, fe0/1 uplinks into a static ospf network. Would HSRP need to be setup on both sides of the 3640?
Posted by: David Lundgren at November 11, 2006 11:51 PM
I suppose I didn't look at the picture long enough. I was distracted by the NAT translation out to the left of the pix. Anyways I now see the virtual IP is on both sides of the routers.
Posted by: David Lundgren at November 14, 2006 9:06 PM
I think you can also make some load-balancing with HSRP. This is a little bit "tricky" but still : You can use two HSRP groups, the first assigns an active router, the second a standby one.
cheers
Posted by: Francois at April 19, 2007 7:00 AM
This looks like the setup we are looking for. However, after testing it appeared there may be an issue with outgoing traffic appearing from the non-virtual ip address of the router. Is that correct? Could it be a nat issue? Any help would be greatly appreciated.
Posted by: Chris at July 2, 2007 5:03 PM
Why not use GLBP? You sated that the client didn't need load balancing.
Anyway, it's always better to let the standby gateway do some stuff instead of doing nothing (load balancing). The only case I go against load balancing is:
1) the standby gateway is very unstable
2) the standby gateway is very slow
Posted by: Mahmoud at September 29, 2007 8:44 AM
For load balencing VRRP sends more hellos which means these packets are shooting every second and may congest a network with alot of users, but may be good for smaller networks. anything flowing through the network takes bandwidth. EIGRP pretty much takes care of the all the routing really well even if you make mistakes. Anyways so why use HSRP?
Posted by: Cam at November 20, 2007 12:44 AM
Can any one explain me that GLBP provides Load balancing but what about VRRP, does it provides Load balancing or not
Posted by: Kashif at February 9, 2008 1:13 AM
Good Document...
I found it very useful while implementing VRRP feature for router
Posted by: Ashok at July 31, 2008 9:17 PM