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

Streiner, Justin streiner at stargate.net
Thu Feb 5 01:01:27 EST 2004

On Thu, 5 Feb 2004, Lars Erik Gullerud wrote:

> On Wed, 4 Feb 2004, Gert Doering wrote:
> However, if used equpiment is an option I'd rather look at finding a
> cheap 7513 chassis and VIPs which should be easy these days - you should
> be able to stuff 20 PA-MC-2T3+ cards (i.e. 1120 T1's) in there and
> still have two PA bays (or a single GEIP+ card) available for uplinks.
> Unless all those T1s start pushing line-rate @ very small packet sizes,
> both options should be able to hack it performance-wise too...

Another thing to consider.  Are any of these T1s currently running routing
protocols or pushing lots of traffic?  How about access-lists? A well-loaded
7513 might be up to the job, but if you're throwing BGP/OSPF/EIGRP/etc
into the mix, that may be another story entirely.  Other questions to
consider - some technical and some business-related:
1) Is the exposure of having all 1100 T1s on one router worth the reduced
	up-front capex on the router?
2) Will more T1s be added over time, and will your design scale
3) Is there a certain expected minimum lifetime to this POP design?
4) How much time does this organization spend troubleshooting problems on
	such a large number of circuits?  How much more or less time would
	the new design potentially change that level of effort?
5) Same as 4) but related to the provisioning of these circuits.

It's been my experience that especially in cases where you're dealing with
this level of circuit density, the less often human hands have to
physically touch equipment, install cabling, etc, the better.

I realize there may be non-technical challenges in doing this, but in the
long run, having circuits delivered to you in larger aggregated bundles
makes an effective business case in terms of long-term cost savings / cost
avoidance, possibly in exchange for larger capex up-front.  If a telco or
a group of telcos is handing you that many T1s, chances are very good they
already have a significant SONET presence in the building.  1100 T1s would
require up to 2200 copper pairs from the CO to you, which in most cases
isn't possible.  1100 T1s could be delivered pretty easily over an OC48.
Telcos are profit-driven too.  They would typically retain more revenue
per circuit by delivering them in such a manner as opposed to single
circuits, or small bundles.

Also, if this POP is for public Internet access, you need to be especially
wary of the effects a DoS attack would have on such equipment.  Even if
its for some company's internal WAN access, that is still a large concern
with all of the ways a new piece of malware can be snuck past a corporate


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