unequal load balancing with EIGRP

[saimbt]

We have a 10 Mbps link on ethernet and a 2 Mbps on serial. we wish to have unequal load balancing.

the sh ip eigrp topo result is

via 10.254.2.66 (30720/28160), FastEthernet0/1

via 10.254.2.54 (1764352/28160), Serial0/1

and the link details are,

BW 100000 Kbit, DLY 100 usec,

BW 2048 Kbit, DLY 20000 usec

I am bit confused on what varience should I use. going by the sh output, i guess the variance should be 55 and going by the formulae,

{(10000000/minimum bandwidth)+ sum of all delays}*256, the varience comes to 125

I guess I am missing something, help pleaseeeeeeeee

-Sai.

[Georg Pauwen]

Hello Sai,

the easiest way to calculate the variance would be to divide 1764352 by 30720, the result being 58. The first value for each route in the topology database is the relevant one.

HTH,

GP

[mheusinger]

Hi,

just a sidenote: any value above 58 should work, because variance gives an upper limit. Something like "how much worse can a route be to be still considered for load balancing".

Just another note on EIGRP. The metrics consider minimum bandwidth along the path and sum of all delays along the path to the destination.

So only looking for the local interface doesn´t allow for calculation the proper values.

As GP stated the values in the routing table are the local metric for the network under consideration.

This is what you need to calculate the required variance.

Hope this helps

[saimbt]

Hi Guys,

First of all a big thanks for the suggestions, I tried a variance value of 58, but still getting the same output in sh ip eigrp topo,

P 10.x.0.0/20, 1 successors, FD is 30720

via 10.254.2.66 (30720/28160), FastEthernet0/1

via 10.254.2.54 (1764352/28160), Serial0/1

-Sai.

[ruwhite]

You won't see any change in the EIGRP topology table--you'll only see it in the routing table. The RD on the 2MB path (28160) is less than the FD for the route (30720), so setting your variance to 1764352/30720=58 should work.

:-)

Russ.W

[Richard Burts]

Sai

Your post sounds like you expect something to be different in the topology table when you configure variance. But the effect of variance is not in the topology table but in the routing table. Do a show ip route 10.x.0.0 and see if both paths show up in the routing table.

HTH

Rick

[saimbt]

D EX 10.x.0.0/20 [170/1764352] via 10.254.2.54, 21:11:15, Serial0/1

[170/30720] via 10.254.2.66, 21:11:15, FastEthernet0/1

-Sai.