Re: Can't Get Carrier from PM3 to Bell Canada

Derric Scott (dtscott@scott.net)
Sat, 21 Dec 1996 13:17:56 -0600 (CST)

We have a PairGain feeding our Internet T1 which goes to an Adtran CSU/DSU.
The Adtran manual shows a straight thru connection where 1&2 are a pair and
4&5 are a pair (not sure which is rx or tx). BTW - we've had a T1 outage
about every 6 months or so and each time it has been one of the PairGain
units dying.... I'm not so sure about their reliability at this point!

So a straight cable should work fine.

Adtran has also told me that FLAT SATIN RJ-45 will work fine for short
distances for the T1 (add this to the other recent thread about
twisted pair, shields, CAT 12345, etc for RS-232 115,200)! Sure, I
completely understand crosstalk, RF environments, etc. but that tidbit
may come in handy one day...

Derric

> On Thu, 19 Dec 1996, Evan Champion wrote:
> > Could you do me a _REALLY_ big favour and check your wiring to see what
> > it is? Was it the standard Livingston wiring? And does your wiring use
> > all 10 pins of the RJ-45? Our wires only use 8, and one thing we thought
> > was that perhaps when they wired up the breakout for the PairGain they
> > started it at off 1 wire off... That would be enough to get the PairGain
> > to report the link is electrically OK because you'd still get 1 of the 2
> > receive/transmit wires hooked up.
>
> That's probably something like what's going on. We just used the cables
> that came in the box with the PM3's and it worked for us. These are the
> two-pair cables with RJ45's on the end, laid out on the connector as one
> pair, then a one-pin gap, then the next pair (so pins 1+2 are RX and 4+5
> are TX?). The Livingston manual isn't clear about whether the pairs in the
> cable are supposed to be crossed over or not (or which way they are
> crossed, if they are) and I'm not partial to the idea of taking 23 of our
> lines down just to check. Our HRU's are locked in a cabinet owned by the
> telco so I have no way of checking how the female RJ45's are wired. :-(

-- 
Derric Scott          Scott Network Services, Inc.         P. O. Box 361353
derric@scott.net           (205)987-5889               Birmingham, AL 35236