HSRP + load-balancing

smothuku · ‎12-05-2007

Dear Experts ,

Please find the attached network diagram.

we want to do load-balancing between E1's which was mentioned in the diagram.

Generally , how to achieve load-balancing using HSRP ?

I know we can go for MHSRP ,, but we do not want to use MHSRP.Any idea ?

Thanks,

satish

lgijssel · ‎12-05-2007

Aren't you making matter more complex than is needed? You should not need to run HSRP at all in this scenario.

Use an ipservices image on the L3switch and run EIGRP or OSPF. The def gw can be located on the switch as well, if that dies there is very little left to recover.

You can then configure your load balancing with the routing protocol and it will all become much easier. In this way you can even load balance traffic to your default route.

regards,

Leo

smothuku · ‎12-05-2007

Hi Leo ,

Thanks for your reply..i know ospf does load balacing and we can do load balancing with eigrp also with the help of variance.

But our concern is how to load balance with HSRP..Any idea.. ?

Thnaks,

satish

lgijssel · ‎12-05-2007

HSRP serves a different purpose, namely to offer a default gateway to hosts in the LANunder all circumstances.

http://www.cisco.com/en/US/tech/tk1330/technologies_design_guide_chapter09186a008066670b.html

Therefore, the use of HSRP is only at some distance related to load balancing. In fact, load balancing is the next step and it can be implemented differently by the vendor on each routerplatform.

In situations where both links are available you will need a routing protocol to specify available paths and their respective loads. Some kind of variance will be needed also because the alternative path has an extra hop (from router1 to router2 via the LAN) and hence also a different metric. This was in fact why I advised you to look at the switch as the def gw because from it's perspective both paths are equal in cost.

Bottomline is that HSRP in itself was not intended to do load balancing, a routing protocol is needed in addition to it.

regards,

Leo

mheusing · ‎12-06-2007

Hi,

Still I am not sure, what your requirements are to rule out a dynamic routing protocol like OSPF, which could be used in conjunction with HSRP. Thus I do not know, if HSRP or GLBP described below will give you the desired results.

If you do not want to use a dynamic routing protocol, you can get sort of load balancing with HSRP by using two HSRP groups per LAN segment. One HSRP group uses f.e. 10.1.1.1 as virtual IP and the other group uses f.e. 10.1.1.254 and have half of the hosts on 10.1.1.0/24 with 10.1.1.1 as default gateway, the other half has 10.1.1.254.

You might want to have a look at Gateway Load Balancing Protocol (GLBP), which offers HSRP functionality plus loadbalancing with a single default gateway IP.

Details about GLBP can be found at "Configuring GLBP"

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a008042fb97.html

Hope this helps! Please rate all posts.

Regards, Martin