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EIGRP Load Balancing over unequal distances???

I have three sites connected via 8Mbps x.21 circuits in a triangle formation. Each site has two Routers terminating each of the links. EIGRP is the routing protocol.

I've been looking into load-balancing around the triangle. Each site has a single hop to the other plus a double hop the other way round. I know EIGRP supports equal/unequal cost loadbalancing, but to a destination of equal distance.

Is there a way to load balance over un-equal distances to a destination??

Thinking about this logically, packets may arrive out of sequence if I send some direct in one hop and some others the long way around in two hops.

Any comments are appreicated.

Thanks,

Wayne

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Accepted Solutions
Purple

Re: EIGRP Load Balancing over unequal distances???

That first bit of my post should have read:

While EIGRP does have knowledge of hop counts,....

Paresh

4 REPLIES
Purple

Re: EIGRP Load Balancing over unequal distances???

Hi Wayne,

EIGRP is just the protocol for what you want to do. It has a concept called variance which install all routes (as long as they are feasible i.e. loop-free) which have a metric less than the best-metric x variance.

A variance of 2, for example, will let you install a second route with a metric upto twice the best metric.

When you use CEF to switch your traffic, there is no danger of packets arriving out of sequence because the load balancing is done on a per-destination basis.

Hope that helps - pls rate the post if it does.

Paresh

New Member

Re: EIGRP Load Balancing over unequal distances???

Paresh, thanks for your reply.

I looked at the variance command but was unsure whether you could unequally load balance across a single hop and double hop links to the same destination.

I assumed it was based on the same distance to a destination but with varying bandwidths and costs where you could use the variance command for unequal load balancing?

Will give it a shot.

Thanks

Wayne

Purple

Re: EIGRP Load Balancing over unequal distances???

Hi Wayne,

While EIGRP does have knowledge, it ultimately works with composite derived from the bandwidth and delays (by default) of the links that make up the path. Therefore, the fact that one of your paths has one hop and the other has two hops is immaterial as far as variance.

Also check out the following like:

http://www.cisco.com/warp/public/103/19.html

And let us know if you need any help to get this going.

Hope that helps - pls rate the posts if it does.

Regards,

Paresh.

Purple

Re: EIGRP Load Balancing over unequal distances???

That first bit of my post should have read:

While EIGRP does have knowledge of hop counts,....

Paresh

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