Is it possible to bond two T1's across two different Cisco Routers?

[texnut]

Hello all,

I am very confused at this point and any help to clarify what I'm about to describe is greatly appreciated.

We are very close to signing a contract with a new voice/data provider. The provider is basically going to give us all our phone lines via VoIP across a T1, and then another separate T1 line for data.

He (they) claim that we will have the benefit of a 3Mb connection since we are getting two T1's rather than just the usual 1.5Mb connection.

That would make total sense to me if we were using one router to control the two T1's and the FXS card however they won't do that...they are providing us with two routers:

a Cisco 2431-16FXS IAD for the Voice and a
Cisco 1721 for the Data.

How can they "bond" the two T1's on our network across two separate routers - is that possible?

Thanks all for any insight you can provide!

 

[Jynxx]

Not possible.

You can implement "load balancing" to a certain extent depending on the routing protocols, but you can not bond interfaces on different routers to do MLPPP for instance.

 

[texnut]

That's what I thought - so what are these guys talking about then? The rep has assured me many times that we will gain the added bandwidth from the extra T1..?

Is there something I'm missing here?

 

[chipk]

Sounds like they're being a little deceitful. While separating the traffic will help, you're not in reality taking advantage of a full 3 Mb pipe.

 

[plshlpme]

the only way that would work as they are describing it is if they would have a third router that they are going to terminate the two t1s into and then feed to you via lan but that wouldn't make much sense either.

 

[texnut]

hmm, very confusing although I suppose it's possible that they may be pulling some "magic" at their end of things.

I'm going to ask to talk to an engineer and have him describe the proprosed infrastructure to me.

Once I have a solid answer I'm going to post back the results.

 

[ADB100]

It is possible but not with the routers you have listed. Multi-Chassis-MLPPP is possible on bigger routers but requires a central router to terminate the PPP connections. It uses L2TP technology and each access router pushes the physical PPP traffic to a central router that re-assembles the various PPP traffic into a logical bundle. I am sure you need some serious routers though 7200VXR's probably?

What I think they are suggesting is load balancing where in theory you get 3Mbs; however you will never achieve 3Mbps throughput between two devices.

HTH

Andy

 

[texnut]

Ok, so I've finally cleared this up.

Looks like what they intended to say was that they would load balance the two T1s across the routers, rather than bond them.

Well - I suppose that will be better than simpily having one T1, right?