Channelizing T3 & Hardware requirement

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Apr 7th, 2008
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We have a heavy bandwidth application that requires point to point connection with our customers. Right now we are using point to point T1 and when required we bundle the T1s for greater bandwidth.


Based on our carrier the break point on the cost of T3 is 6 T1s which we've alredy surpassed.


So I wanted to know if I order the T3 from the carrier would I be able to channelize it into multiple T1s? If yes what is the minimum router model and module I would need. Can the 3800 series router handle this?

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paolo bevilacqua Mon, 04/07/2008 - 11:50
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Absolutely no need for external devices when using channelized T3. You can use as small as a 7200 router with PA-MC-T3 and you're all set.


Hope this helps, please rate post if it does!

Collin Clark Mon, 04/07/2008 - 11:54
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Small as a 7200! Check the price between the two, there is a huge difference.

paolo bevilacqua Mon, 04/07/2008 - 12:06
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Beside the fact that7200 with npe-400 can be had very economically on the used market, when you have many T1s possibly with services enabled, even a 3800 router doesn't really do the job, so so migrating to a proper edge-class router is necessary anyway.


Furthermore the cost of a full equipped M13 mux plus the interfaces in the router makes so that having the hardware in the router makes that solution more economical.



Collin Clark Mon, 04/07/2008 - 12:17
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I disagree. The T3SU will terminate the T3 and split the DS3 into multiple channels with the physical hand off being a HSSI/V.35/DSx. This solution is cheaper for both the T3 end as well as the customer edge (say a 2811 with a HSSI interface).

paolo bevilacqua Mon, 04/07/2008 - 12:29
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Of course you are entitled to your opinions.


But do the math and check what is better between an octopus cabling for like 20 x T1 to an external device, and a clean, purely router based solution.


Channelized interfaces have been an excellence point for cisco and have always been received positively since introduction more than 10 years ago.

Collin Clark Mon, 04/07/2008 - 12:38
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Why use and Octal cable when you can use a single HSSI interface? I have not heard of Cisco being able to channelize from a T3 to multiple sub-rate interfaces on the same chassis (HSSI, V.35, IMA, DSx). Provide some docs if you can.

paolo bevilacqua Mon, 04/07/2008 - 12:55
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I didn't say octal, I said octopus like in the sense of multilegged connection.


Anyway, when using CT3 that remember is alway M13, that is comprised on individual T1s, one common need is to inverse multiplex "some" of these T1sm like in the question that originated this thread. This is perfectly possibly and you have either MLPPP or CEF load balancing without the need of going thru an intermediate speed interface.


In other words, the niceness of all that is having a single interface going into telco and then you reconfigure things as you like better without touching or changing hardware anymore.


If that doesn't appeal to you, as I said before, that's fine with me. But please do not take a challenging attitude toward myself as I don't really need to prove anything to anyone :)

mparekh Tue, 04/08/2008 - 11:45
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If I channelize the T3 into individual T1s would I be able to bundle the some of the T1s using multilink PPP?




Collin Clark Tue, 04/08/2008 - 11:47
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Yes or you can bundle them into a higher speed interface like HSSI.

paolo bevilacqua Tue, 04/08/2008 - 13:06
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Yes, but when using an external multiplexor to bundle T1s, a matching unit is needed on the two sides of the circuit. A MLPP or CEF load sharing does requires the router only.

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