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Load balancing traffic 2 ISP's

Level 1
Level 1

Hi Experts,

One quick question. ( I hope this is easy). I would like to be able to load balance internet traffic on a Cisco 2621XM running IOS version 12.2(8)T5. My goal is the following:

Send 75% through 1 ISP and 25% to a second ISP.

What would be the commands to do this?

I'm not using any routing protocol.

Make up config can be like this:

Inside network:

Outside Interface of router S0/0:

Outside Interface of router S0/1:

Let us pretend that we want to send 75% of the traffic through serial S0/1 ip



4 Replies 4

Level 1
Level 1


the above stated scenario can be achieved by implementing Igrp/Eigrp with variance.

The difference between other protocols and Eigrp is that it has the ability to do Unequal Cost load balancing.

The variance command decides the variance of distribution of load on each link.

The default is 1 which enables equal cost load balancing.

The traffic-share balanced command distributes the traffic according to the default metrics in combination to the Variance command.

A thorough knowledge on how variance command is used is nessacary,

Example : the Example below sends 2 packets on 1 interface and 1 packet on another interface.

router eigrp 1


variance 3

traffic-share balanced

Level 1
Level 1

Hi Randall,

You can acheive this by using PBR I guess... on the incoming interface configure PBR to match certain subnets (using access-lists) and configure next hop to be either of the ISP links.

If you requirea any detailed config example, let me know.


Anish Paul Behanan.

Further to add for above solutions--

i) Assuming you have Single ISP for both the links,you must ask your ISP to run eigrp/igrp on their router too.

ii) When you implement PBR , automatic failover will not happen.Ofcourse to do automatic failover some extra config is required if your ISP is also cisco router.

Level 1
Level 1

You can use Linkprof from Radware.

Their solution works like magic. It basicly using NAT to do two way loadbalancing with diffrent ISP's.

You don't need to use the same IP addresses with diffrent ISP's. You can loadbalance incoming traffic to your servers.

Lot of features, I really like their solution to the problem.