Gateway Load Balancing Protocol and 2 ISPs

Unanswered Question
Sep 4th, 2008
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Will GLBP do load balancing between 2 ISPs which are connected to 2 interfaces on the same router?

In other words, I have only one router with multiple physical interfaces.

Interface0 will be connected to ISP1

Interface1 will be connected to ISP2

and Interface2 is connected to the Inside network.

Will I be able to use this protocol for failover purposes in case one ISP goes down?

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merryllem Thu, 09/04/2008 - 15:50
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The answer is NO. The router will not even allow to do this configuration. Basically GLBP pairs (interfaces) have to be in the same subnet and you CANT configure two interfaces from the same router with the same subnet (e.g F0/0 = and F0/1 -

In my opinion Load Balancing is over rated when it comes to internet use. Try to keep to everything simple unless there is a really a NEED for it.

However Redundancy you do need. Will be using BGP with your ISP?

If you are use the link below for reference

insccisco Thu, 09/04/2008 - 16:45
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The router will stop you if you try to configure 2 of its interfaces in the same subnet?

Based on your input, I can then assume that if I have 2 routers with their outside interfaces pointing to each ISP, then GLBP, thus failover, will be possible... right?

If my assumption is right, I'd love this idea because glbp will not only give you redundancy in case one of the routers die, but also it will give you load-balance.


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