asterisk users - Oct 2004 - Digium Wildcard T1 Compatibility (ethernet f or T1 cables)

<snip>
>RJ48C is *not* standard ethernet cable. The twisted pairs are grouped 
differently. Ethernet cables work OK for T1s if they are only 2 or 3 
metres long. Long ethernet cables give high error rates when used for T1s.

Regards,
Steve

<snip>


I have run several robbed-bit(non-PRI) T1s on standard CAT5e ethernet cable
for runs of over 100 feet(30 meters) and have seen no increase in the error
rate of the T1s. I've done this for years, and even the telco install techs
say it really doesn't matter especially if you are running robbed-bit,
supposedly its more forgiving than PRIs are. 

MATT---

mattf wrote:
><snip>
>
>  
>
>>RJ48C is *not* standard ethernet cable. The twisted pairs are grouped 
>>    
>>
>differently. Ethernet cables work OK for T1s if they are only 2 or 3 
>metres long. Long ethernet cables give high error rates when used for T1s.
>
>Regards,
>Steve
>
><snip>
>
>
>I have run several robbed-bit(non-PRI) T1s on standard CAT5e ethernet cable
>for runs of over 100 feet(30 meters) and have seen no increase in the error
>rate of the T1s. I've done this for years, and even the telco install
techs
>say it really doesn't matter especially if you are running robbed-bit,
>supposedly its more forgiving than PRIs are. 
>
>MATT---
>  
>
Your mileage many vary, as they say. I've had problems on T1 and E1 
cables as short as 10 metres. Changing the pairing stopped the errors 
completely.

You said you can see no *rise* in the error rate. If the error rate is 
even measurable, I'd say it is too high. I can usually leave a link for 
weeks, and it records zero errors.

Robbed bit is more forgiving for dropped calls, as sensible terminals 
persistence check the signaling. The audio suffers just as many clicks 
and pops, though.

Regards,
Steve

--On Monday, October 25, 2004 09:36 -0400 mattf <mattf@vicimarketing.com> 
wrote:
> <snip>
> I have run several robbed-bit(non-PRI) T1s on standard CAT5e ethernet
> cable for runs of over 100 feet(30 meters) and have seen no increase in
> the error rate of the T1s. I've done this for years, and even the telco
> install techs say it really doesn't matter especially if you are
running
> robbed-bit, supposedly its more forgiving than PRIs are.

A good Cat5/Cat5e cable will perform just fine at the signalling and drive 
levels of a T1 -- 3V signalling at like...hmm can't remember MHZ but if 
anyone's in that interested I'll look it up.

The problem happens in that a lot of people mis-wire them, or wire an 
ethernet crossover that doesn't' work right for a T1.  T1 uses pin/pair
1-2
and 4-5, ethernet uses different pairs.  Then they make the crossover 
ethernet style and mess it up, or invert some of the T1 signaling pairs so 
there's a mis-match.  Or run the cable close to noise sources (fluorescent 
light ballasts are my personal bane)