T! crossover cable
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Posted by Rich Piehl on September 3, 2006, 12:53 pm
Please log in for more thread options I have a customer that currently has ground start and Tie channels on a T1 from AT&T. They were supposed to be switched to a T1 from McLeod last week, but Mcleod missed a couple of numbers that needed to be ported so the switch got delayed. The current T1 connection to the PBX is an RJ 45 plug plugged into a CSU. But in talking with the McLeod tech he said I may need a T1 crossover cable to make the new T1 work. I'm familiar with Ethernet crossover cables, but can't locate anything on line about T1 crossover cables. I'm trying to be proactive here, and if I need to make up something would prefer not to do it on the fly by the seat of my pants. Can someone direct me to info, provide info, etc. TIA Take care, Rich God bless the USA -- Freedom requires work and sacrifice. Tyranny you can have by doing nothing. Author unknown | ||||||||||||||||||||||
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Posted by Al Gillis on September 3, 2006, 1:39 pm
Please log in for more thread options Hi Rich... I'd be quite surprised if you'd need new cables to move a working DS-1 from one service to another, especially if the same access provider is being used. But... To make a "DS-1 Crossover cable" wire it like this: On the "Left" one end of the cable wire pin 1 to pin 5 on the "right" end and pin 2 on the "Left" end to pin 4 on the "Right" end. And vice versa (4 & 5 on the "Right" end connect to 1 & 2 on the "Left" end. (If it makes more sense to you subsitute CSU for "Left" and PBX for "Right"!). Making these connections connects the transmit signal on one end of the cable to the recieve signal on the other end while keeping the tip and ring conductors "straight". Good luck! Enjoy a fun and safe holiday! Al | ||||||||||||||||||||||
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Posted by Doug McIntyre on September 3, 2006, 1:43 pm
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>... But in talking with the McLeod tech he said I may need a T1
>crossover cable to make the new T1 work... You won't be able to find one in a store, you'll have to make it, or change things around. You may be able to find one on eBay for CCNA's doing testing or the like. Most likely what he meant is that the tech might have reversed the pairs when they installed your new T1. They frequently don't check to see if their pair polarity is correct on their T-BRD sets when they test them. I know I've had to fix this sort of problem dozens of times when I've been onsite installing routers and such. A T1 is pined out on an RJ-45 to be receive on pins 1 & 2 and Transmit on pins 3 & 4. This is different pins than what Ethernet uses, so an ethernet cross-over won't work. You can make your own T1 cross-over cable by simply reversing pin 1 and 3 and pin 2 and 4 end-to-end. Or, what is probably easier, is to go into the jack, most installer techs use a screw-down terminal jack, move the cable on pin1 over to the one on pin3, and move the cable on pin2 over to pin4. Then it'll be wired correctly for the future instead of having a special cable that you'll forget about in the future. | ||||||||||||||||||||||
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Posted by Touch Tone Tommy on September 5, 2006, 2:27 am
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It's actually Pins 1/2 and 4/5, so take a dual surface jack, install 2 Cat-5 jacks, and use some scrap wire to go from the Wht/Blu pair of one jack to the Wht/Org (568-B wiring pattern) of the other jack, and vice-versa. Use a regular Cat-5 patch cord with this fixture, and if you find that it solves any problems, rewire the actual jack for the T1 and don't leave the adapter in service. >>... But in talking with the McLeod tech he said I may need a T1
>>crossover cable to make the new T1 work... >
>You won't be able to find one in a store, you'll have to make it, or >change things around. You may be able to find one on eBay for CCNA's >doing testing or the like. > >Most likely what he meant is that the tech might have reversed the >pairs when they installed your new T1. They frequently don't check to >see if their pair polarity is correct on their T-BRD sets when they >test them. I know I've had to fix this sort of problem dozens of times >when I've been onsite installing routers and such. > >A T1 is pined out on an RJ-45 to be receive on pins 1 & 2 and Transmit >on pins 3 & 4. This is different pins than what Ethernet uses, so an >ethernet cross-over won't work. > >You can make your own T1 cross-over cable by simply reversing pin 1 >and 3 and pin 2 and 4 end-to-end. > >Or, what is probably easier, is to go into the jack, most >installer techs use a screw-down terminal jack, move the cable on pin1 >over to the one on pin3, and move the cable on pin2 over to pin4. > >Then it'll be wired correctly for the future instead of having a >special cable that you'll forget about in the future. | ||||||||||||||||||||||
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>from AT&T. They were supposed to be switched to a T1 from McLeod last
>week, but Mcleod missed a couple of numbers that needed to be ported so the
>switch got delayed.
>
> The current T1 connection to the PBX is an RJ 45 plug plugged into a CSU.
> But in talking with the McLeod tech he said I may need a T1 crossover
> cable to make the new T1 work.
>
> I'm familiar with Ethernet crossover cables, but can't locate anything on
> line about T1 crossover cables. I'm trying to be proactive here, and if I
> need to make up something would prefer not to do it on the fly by the seat
> of my pants.
>
> Can someone direct me to info, provide info, etc.
>
> TIA
>
> Take care,
> Rich
>
> God bless the USA
> --
> Freedom requires work and sacrifice. Tyranny you can have by doing
> nothing.
>
> Author unknown