Multilink with Multiple Cable Modems

Is there a way with any Cisco equipment to Multilink 2 or more cable modems. I have done it with T-1's, but never with cable modems.

In my case, I could actually afford to put in 18 cable modem services (the cable company here is cheap) for the cost of the T-1 that I have now.

I would like to multilink at least two cable modems together, even if the muxing isn't true, any little bit would help. This is a small time cable company, so BGP probably isn't an option, this is going to have to be something I do myself.

Thanks for any advice.

Reply to
N. Hall
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First to answer your question. Not sure about Multilink as I don't tend to use that. But, you can easily utilize all the bandwidth by using a load balancing routing protocol.

That said, I really don't like that set up. It may not be as attractive as it looks...

Very likely, the business cost of a cable modem is not the $40 you would pay as a home user. I know with Time Warner it is not ($80-100 depending on contract). That is just for bare minimum speeds. Also, if you have a

3Mx256k connection, the best you will ever have from one of these is 256k (on a single connection). Each end will only be able to upload at 256k. Yes, 18 of these is more than a T1. But, you have latency to consider. You'd be lucky to get 25ms or less, even with a single ISP, while a T1 will offer
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Let me clarify a few things regarding my earlier post. I already have the business class cable modem service installed (for 1/18th the cost of the T-1) and the T-1 is still also installed there as well. I have a VPN tunnel from a Cisco 831 Router on the Remote side, into a Cisco 3005 VPN Concentrator on the other side. I have done extensive testing to compare the T-1 to the Cable Modem, and basically the cable modem provides roughly double the download speed of the T-1, and about half the upload speed of the T-1 (all measurements are over the VPN tunnel downloading and uploading files from / to a internal server).

I had put a few users onto the cable modem service and they found it to be superior to the T-1, however now I have added more users and the slowness complaints have returned just like they did on the T-1.

So, optimally I would like to get two cable modems installed, from may analysis this should provide roughly 6 mbps of downstream, and about 1.5 mbps of upstream. Is there any VPN capable Cisco equipment that can multilink the two services together?

My other less desirable option would obviously be to run two separate 831's with two separate networks and tunnels and load balancing them that way.


Reply to
N. Hall

That does clear up some things. I am curious about one thing though.... You said your bandwidth tests were over the vpn and you were getting 3Mb downstream. How does site A get 3Mb downstream when site B can only send at

1.5? I understand it can get that from the internet, but not from the other site.

Anyway, I believe Pix may do what you want. They are suppose to support ospf now. I think you are going the right way by doing the field test before making the executive decision to switch over.

Also... considering that you really need to purchase both ends of the cable connection, 2 connections = 4 cable services. 18x a T1 seems really expensive. I'm curious what you are paying for a T1 circuit. How far apart are the locations? Are you crossing lata lines?


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At the risk of not answering your question, can the ISP not be twisted into giving you a 12 meg download limit? after all cable will go to something like 34 meg.

Reply to
John Smith

This won't help. The limiting factor is the upload, since it is lower and this is an end to end solution. However, the cable company does probably offer higher upload speeds as well. He can, perhaps get a 2Mbx2Mb - or possibly more.

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