Re:Load balancing in Point to Point Connectivity

[CSCO11776584]

Hello to Everyone,

I am looking for a solution for Load Balancing/Failover. Basically I have two 1841 Routers having point-to-point connectivity, connected through Serial Interfaces. I want to have Load Balancing/Failover between the two routers. IOS running on both the router is IOS BASE M 12.4. I have the following questions:

1) Which Protocol can I use to achieve Load Balancing and Failover?

2) Do I need to upgrade the IOS?

3) Is there any examples of the configuration to achieve this.

Your assistance is greatly appreciated. I am attaching the topology for your reference.

Thanks in Advance!!!

Regards,

Prashant K

[Vivek Ganapathi]

Hi Prashanth,

I would suggest you to simply go with a floating static route. You can have the respective routes pointed to your primary link & the same routes pointed to another link with a higher metric value. Example as below

ip route 10.1.0.0 255.255.0.0 Serial 0/0/1

ip route 10.1.0.0 255.255.0.0 serial 0/0/0 100 <-- By specifying 100, you will make this path as backup.

Regards

Vivek

[CSCO11776584]

Hello Vivek,

I wanted to know whether load balancing would be 50-50. Also, is there anyway I can specify ratio like 60-30 for load balancing.

Regards,

Prashant

[Vivek Ganapathi]

Hello Prashant,

If you are looking at achieving the ratio of 60:30 then you need to use EIGRP to achieve this. Yes, you can achieve that ratio / unequal cost load balancing in EIGRP provided you tweak the composite metric calculations parameters.

With static routing example i provided you above, that was only for failover. You can achieve the load balancing by not specifying the higher metric value. CEF will use the per-destination based load balancing. Whatever 50:50 exact is not possible logically.

Regards,

Vivek

[CSCO11776584]

Hello Vikas,

If I am correct, by configuring two static routes on both routers without mentioning metrics, load balancing would be about 50-50 and if one link goes down, failover happens. There is no need to upgrade IOS on routers(Present is IOSBase M 12.4).

Regards,

Prashant

[Vivek Ganapathi]

Prashanth,

You are partially right. Configuring two static routes without metrics the load balancing would happen, but it wouldn't be 50-50 (approximately near). The reason is, the load balancing algorithm is based on Cisco Express Forwarding (CEF) which is Per Destination.

Hope it's clear.

Regards

Vivek