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how to configure two isp in one Router

By trackme ·
Dear all,
I have a cisco 2511 router with 2 serial and 1 ethernet interface.we are planning to implement two isps on the same router.
Can you tell me how i can do this ,is it possible in this Router.
My intention is to have both the lines in the same Router,so that even when one line is down,my users can still work on the internet....
what is the best possible solution for that.

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by germain In reply to how to configure two isp ...

The simplest way is you can put two static default routes on the router to get out. If they both have the same weight, they should load balance. If one goes down, the other takes all the traffic. Or if you prefer one over the other, you can give that one a lower weight. But you may have problems with traffic getting back in. Not sure if the traffic will come back in the same ISP it went out. That all depends on how your nework is set up (i.e., Firewall, NAT, public vs. private desktop IPs, etc) You can also use BGP which is a little more complicated.

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by peeyush_maurya In reply to

You can add a lower administrative distance on the one you want to be used first. You should not use the permanent keyword as it will remain in the routing table even if one interface goes down.

ip route <ip of fastether> <ip of s1/0> 10 <-----administrative distance (lowest will be added to routing table first)
ip route <ip of fastether> <ip of s1/1> 20 <-----will be added to the routing table if the first route is removed/interface goes down

hope it will work...

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by peeyush_maurya In reply to

sorry to bother u again.. :)

On a router you can put mulitple routes in for a default gateway such as:

ip route <--ip of ur Serial port 0
ip route <--ip of ur Serial port 1

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by dplewis In reply to how to configure two isp ...

None of these methods would provide true load-sharing and resilience - for incoming services you are tied to one ISP (the ISP which "owns" the IP address for the service). For outgoing, the return traffic would not load-share (even with BGP).
The only way of doing this is to use an extra layer of intelligence - including, for instance, maintaining authority for your domain names yourself and performing "clever" name resolution based upon availability, load-sharing etc. Look here for such a product:

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by Choppit In reply to how to configure two isp ...

I've used the ISB Pro800 Turbo and found it quite good. Nexland has now been taken over by Symantec but I believe some of the Symantec firewall appliances were originally deigned by Nexland and have similar functionality.

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