Load balancing

Unanswered Question
Feb 6th, 2009


I have a router with 2 wan link from different ISP .

How could i do load balancing and avoid asymmetric routing .



I have this problem too.
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Giuseppe Larosa Fri, 02/06/2009 - 02:29

Hello Vishwa,

have you got your own public ip address block or are you using address pools provided by the two providers ?

Are you using BGP or simple static routes?

If you have your own IP address block and you advertise it to both ISPs you can face some asymmetrical routing but it shouldn't be a real issue unless your border router is also acting as a firewall.

To avoid asymmetric routing a strict hierarchy primary/secondary is more suitable.

Hope to help


Joseph W. Doherty Fri, 02/06/2009 - 04:48

For equal static outbound load balancing, most routing will support it. For dynamic outbound load balancing, Cisco's OER/PfR might be possible.

To avoid asymetric routing, don't advertize the same addresses blocks to both ISPs.


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