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ISP Load balancing / failover


We are having one router connected to two ISPs. We need to load balance betwwen two ISPs. Also our website is published by ISP 1. Obviously , we need that website is available even if link to ISP 1 fails. Then ISP 2 should publish our website. How to do this , something to do in DNS - so that secondary address will be picked up by user in case first ip ( ISP 1 ) is not available. Also if possible we need load balancing in these links for outgoing tarffic.

Any experience pls share.

any link on is highly appreciable.


Hall of Fame Super Gold

Re: ISP Load balancing / failover


for redundancy for website to be reached from outside, you have only two choices: BGP or an appliance that does the trick using DNS.

Apparently, the leader in doing the appliance solution, is linkproof by radware. I would suggest an equivalent solution by cisco, but it seems there is none at the present time.

Both solutions are expensive, but the appliance is simpler to implement and maintain.

There are no other solutions for when you have the website in house. Of course you can place in a datacenter or hosting service and this is the usually the best choice as you don't have anything anymore to worry about.

Hope this helps, please rate post if it does!

New Member

Re: ISP Load balancing / failover

The Cisco solution for this is the Global Site Selector.

It is a very inexpensive appliance that works in combination with our (or third party) server load balancers (or IOS SLB, or individual hosts) that has a host of tricks available to it to ensure your uptime, the primary of which is DNS but includes Reverse Route Injection among others.

Unless the exact same range of addresses is advertised via multiple providers, there is very little hope of keeping individual sessions alive - once one address or range of addresses becomes unavailable connections to it will necessarily be terminated. don't believe the bit about requiring Cisco Network Registrar, it will work fine with whatever DNS solution or load balancers you have today.


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