PA-MC-T3 vs. External MUX on 7206VXR

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- trbodsl
  
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posted
17 years ago

Thu, Jul 27, 2006 1:37 PM

Hi All,

I'm at a point where we are looking at getting a DS3 to aggregate most of our 31 T1 circuits on to. The telco is giving us a whole slew of reasons why this is a good move, and I tend to agree with them.

Here's my predicament:

When we first built this network back in 2K3/4, facilities were not available for a DS3 near our building. The build out of this would have cost about $60-80K and pushed back the implementation about 12 weeks. At that time, getting a DS3 was not practical. Now, our new account rep wants to put the DS3 in to our building at no cost, except for the loop. Seems as thogh facilities are now available and they are anxious to get away from maintaining all the copper in the building.

As of right now, I have a 7206 with 4 of the octal T1 cards (PA-MC-8TE1) in the chassis. The telco originally wanted to sell us an Adtran mux to channelize the DS3 and give us 28 T1 ports that I would have to put back into our router as T1. I spoke with their Cisco engineer and asked him to investigate the options of plugging the DS3 directly into the 7206VXR. They came back with the PA-MC-T3 card, at a cost of around $10K.

I'd much rather perfer putting the DS3 card into the 7206 and bypassing the mux altogether, but I think it's going to be a hard sell to my boss to say that I'm going to see $6K worth of benefit from the DS3 card. This will be my first experience with DS3. I know there is additional diagnostic information you can get by having the DS3 card directly in the router, as well as you eliminate the additional point of failure of the mux.

If I can convince him, would it be better to obtain a PA-MC-T3 card off of eBay? I can get two for at or less than the price of one new one. I know the lower end Cisco stuff is counterfeited quite a bit, but I don't know much about the modules, etc.. for the higher end chassis.

Thanks, Don

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- Hans
  
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posted
17 years ago

Thu, Jul 27, 2006 2:24 PM

When I worked at a very big ISP we used the PA-MC-E3 which could handle 16 * E1. This was really interesting since our Telco delivered an E3 directly to our premises and they configured the customers E1's on these channels. They muxed the E1's into the E3's. Either via a Nortel TN1X or via the Alcatel Daccs.

I assume for the PA-MC-T3 it will work the same. You maybe also want to consider the channelized STM1/OC3 PA which is probably way too expensive. We used these cards as well without problems. Only think you might want to consider: what happens if the E3/DS3 circuit goes down or if the Card breaks. You will loose all T1's at once which can be painfull. On the other hand: they will bring in fiber to your building (I assume) which is much better and probably (dual-feed) more redundant than just copper.

Hans

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- Doug McIntyre
  
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posted
17 years ago

Thu, Jul 27, 2006 7:24 PM

Only 12 weeks? Thats overly optimistic for telco buildouts.

They probably don't care about the copper for 31 T1s. More likely is that they spent some money to get a SONET mux into the building, and now they want to have something on it to justify it :)

The Adtran M13 MUX's are pretty reliable, but having all the T1s terminate right on the chassis is even much more so. The PA-MC-T3 card is pretty nice.

Well, the MUX probably won't fail so much, especially if you get redundant controllers and redudant power supplies. But You can have cabling failures. Yes, you can do alot of testing off the PA-MC-T3 card, you can do latchup remote loops, and do bert tests right from the router chassis. One less device to monitor for circuit failures.

(Not related to if you go for an external M13 MUX or the MUX right on the cisco interface card), when the telco sees you have your T1s ride the higher facilities in, its saves on them having to troubleshoot two sides of a failed circuit, cuts down repair time quite a bit if they only have to investigate one end for problems.

I wouldn't think that you could counterfeit a PC-MC-T3, there's custom ASICs on it. The low-end stuff can be, because its just FPGAs with an external EEPROM.