How to bundle 2 T1's on 2 separate routers

Unanswered Question
Jul 16th, 2007

I have 2 routers with 1 T1 on each going to the main office. The routers are configured in HSRP.

In this scenario only 1 T1 is used at a time.

Is there a way to bundle separate routers like MLPPP? And how would i set it up?

Thank you.

I have this problem too.
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Richard Burts Mon, 07/16/2007 - 07:26


There is an option that you might consider which is multi-chassis multilink. It enables miltilink bundling of PPP serial interfaces on different chassis (in your case on the 2 routers). I believe that this could work for you. Whether it is worth the extra complexity in configuration and the extra overhead of the communication between routers to coordinate the multilink is something that you would have to decide for yourself.

I would suggest that there might be another alternative which you could use. You could consider configuring 2 HSRP groups. You could make router 1 primary in one group and make router 2 primary in the other group. You then configure the end stations so that one half have their default gateway in the first HSRP group and the other have their default gateway in the second HSRP group. This would give you distribution of traffic over both T1s and in the event of a failure of a T1 or of a router then all traffic would use the surviving T1 (or surviving router). In doing this you probably would want to track the local T1 in each of the HSRP groups (especially important in the primary group). And this would take care of getting traffic out over both links. You would need some mechanism to get return traffic to use both links.



Paolo Bevilacqua Mon, 07/16/2007 - 07:56

This is a classic problem. The alternative to Rick's good advice would be to tweak routing so that the HSRP router sees two equal default routes, one via serial, other via other router.


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