Redundancy, Load Balancing and Gateways of Last Resort

Unanswered Question
Apr 18th, 2002
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Compared to other questions, mine seems a bit "juvenile," but here goes anyway.I have two 1720 routers connected to each other by two Point-to-Point T1s. I'll call them router 'A' and router 'B'. Router 'C' is a cheap-o DSL router (soon to be a new T1 to the 'net). So, the network looks something like this:


Router B:



Router A:



Router 'B' sends all packets not on it's network to Router 'A.' Router 'A' has NAT translating the incoming packets (172.16.3.x) dynamically to Access to the internet is through the DSL Router 'C' ( I know that there is a problem with the 172.16.x.x/24 addresses because of the routing when I try to get the second T1 running (s1). How can I get both T1s to work? I want load balancing AND redundancy (one fails, the other stays). How would I do that?

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cantoron Thu, 04/18/2002 - 17:14
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I don't think that is a problem. It works OK for me. What is your problem?

trob Thu, 04/18/2002 - 18:57
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All you need to do is set up static routes that are dublicated for both T1s. I would point them to the IP address of the far-end interface rather than out the local interface. If a T1 drops and the far-end IP is unreachable, the router will not forward traffic across that T1. If the static directs traffic out of an interface but the local interface stays up (statics across a LAN) the setup will drop every other packet. The same will work for your default routes.


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