[c-nsp] Adtran MX-2800 to PA-MC-T3

[Greg Boehnlein]

On Tue, 2 Aug 2005, Bill Wichers wrote:

> 
> > Hello,
> > 	We have a problem that we have exhausted all available resources
> > on solving, and we are running into a dead end. We have several T1
> > circuits, from various LECs provisioned into a single MX-2800 MUX at our
> > location. We then tie that mux into a PA-MC-T3 card on a 7507 in a
> > VIP-2-50 to terminate the circuits. The DS-3 cabling is 25 feet in
> > length and we have (per Cisco reccomendations) a 6 db attenuator on the
> > PA-MC-T3 RX leg. We are running CBIT, w/ the MUX providing timing.
> >
> > We continue to receive LCVs, C-Bit and P-Bit framing errors, and the DS1
> > circuits will occasionally bounce.
> 
> Sounds like a clocking issue. All the T1s need to be in sync, and you have
> to have one common master clock source coming from somewhere. If you don't
> have a master clock, or if the T1s aren't all really synchronous (a real
> possibility with multiple carriers), then you might get time slips which
> can cause all kinds of wierd framing errors. I have seen similar problems
> on circuits that have both ends set to 'slave' for timing.

Yes, but wouldn't those errors manifest themselves at the DS1 level and 
not at the DS3 level? We have 1 way LCV errors INBOUND to the Cisco from 
the MUX (I.E. the Mux side is clean).
 
> See if you can get it so that *your mux* provides timing for *everything*
> (including ALL the T1 circuits). Some carriers let you be the master for
> timing which can make it much easier to setup a system like you have. Then
> set all your remote T1 equipment to 'slave'. You might also want to have
> the MUX derive timing from the DS3 so that the PA-MC-T3 is the master
> timing source for the system.

I can certainly go down that route. However, working with SBC, X/O and ICG 
to try and get that accomplished may be like pulling teeth. I might just 
be better off selling the PA-MC-T3 and the MUX and getting PA-MC-8T1 
cards.

> > I CANNOT find anyplace to buy the ATTEN-KIT-PA online. Our thoughts are
> > perhaps we can use progressivly higher attenuation (10,12,16,18 db) but I
> > cannot order the kit anywhere. Cisco directs me to Insight, who doesn't
> > stock it.
> >
> > Anyone have any suggestions?
> 
> A DS3 just needs a 75 ohm attenuator. Easiest way to get those in a hurry
> is to get them from a TV/video supply place (try
> http://www.mcmelectronics.com). Get an attenuator of the value you want,
> plus one F-to-BNC adapter and a BNC-to-F adapter. You can then use that to
> test. If it works, you can get a BNC attenuator (which will be harder to
> find and more expensive than the "F" type units) from a professional video
> supply place. I'd try working with the timing first though, or just get a
> longer DS3 cable made of 735 cabling (735 is the smaller DS3 cable). 735
> has more loss and is also easier to handle, so it's generally a better
> choice for short runs.
> 
>      -Bill
> 
> 
> *****************************
> Waveform Technology
> Systems Engineer
> 

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