>
> They split the second pair to make the third pair ride in the center
> pins.
> The center two pins are 'reserved' for POTS service in an rj48c and
> need
> to be on the same pair.
Since I troubleshoot T1's for a living, here's my $0.02 worth on the
subject. In an ethernet cable, the pairs are not "split". The first pair
(the white/blue blue pair for those of you following along at home) is
on pins 4 and 5. This conforms to the RJ48 wiring standard and Bell
System color code. The second pair (white/orange orange pair) is on pins
1 and 2. The third pair (white/green green pair) is on pins 3 and 6. The
fourth pair (white/brown brown pair) is on pins 7 and 8.
I just got back from a weeklong troubleshooting school, and we discussed
at great length the use of flat satin cables on T1 circuits. It's not a
good idea. Period.
Here's why. The twists in the wire must be maintained (you shouldn't add
twists or untwist the wire) and must not be changed in order to ensure
Near End CrossTalk does not creep into the cable. This is most critical
in punchdown blocks and jacks where wiring is terminated. You should
only have apporximately 1/2 inch of the sheath exposed when punching
down pairs.
On a side note, T1's use bi-polar signaling, secifically bi-polar return
to zero.
-- Kyle Platts Network Engineer !NTERPRISE Networking Services - To unsubscribe, email 'majordomo@livingston.com' with 'unsubscribe portmaster-users' in the body of the message.