[nsp] Suggestions on terminating a bunch of T1's

Streiner, Justin streiner at stargate.net
Wed Feb 4 16:15:48 EST 2004

On Wed, 4 Feb 2004, Jim Devane wrote:

>             I am attempting to design a fabric that will be able to
> terminate 1100 T1's in one POP. I know, the good sense would suggest that
> the T1's be terminated at the individual CO's and then backhaul the IP
> traffic to the POP but that is not politically a solution. So the problem I
> have is a slew of 4 pair T1's showing up at my cage. Here is what I have
> thought of for solution but I am really looking for more sensical ways.

> Wrap the T1's into 40 M13's.
> Run the channelized DS-3's to a 7206 VXR full of PA-MC-2T3+
> I would need 4 7026 and use one of the PA's for an uplink of some sort.

This is a common design.  As long as the telco is willing to roll the
4-wire T1s onto an M13 muxed DS3, this can be pretty feasible and
potentially make the T1s cheaper if the telco bills you for each channel
termination.  Of course many telcos either don't offer a pricing break on
the T1s based on channel term, or will continue billing you for it until
you ask about it :-)

One thing I can say is that especially in large aggregation scenarios like
this it's generally better to minimize the number of electrical (copper/coax)
to optical handoffs or vice versa.

> Second place design (but not thought out to completion. )
> Wrapping the T1's into a 15454 onto DS-1-14 cards and using a DS-3Transmux
> card to eliminate the M13
> But it is more expensive and I am not sure how I will get the timeslot <->
> IP done unless I employ another box. Any suggestions on how to finish this
> design using the 15454 ? I am not as familiar with the box as I probably
> should be.

The 15454 is just a circuit aggregator/WDM node, it has no IP routing
intelligence built in as I understand it.  You could pipe these out the
back of the 15454 as channelized OC12s, but as you state below, that can
be expensive.

Perhaps the telco would be willing to do the muxing for you and just hand
you 4 OC12s to handle the M13 DS3 channel loads?  You would still need
7600s, GSRs or something similar to handle them and do IP-type things with

The telcos may or may not do this and may or may not make it prohibitively
expensive, but it may be an option worth pricing out.


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