[c-nsp] cat6 gigE

[Jason Alert]

> Cat6 is pretty much the current standard since it's considered to be
the
> most future proof. IMHO, it's fiber time for gigabit and up, but
that's
> partly because I do mostly optical transport these days :-)

Cat5e makes the most sense in a majority of situations since it supports
1000Base-T (IEEE 802.3ab) at distances of 100 meters.  Cat6 isn't
required for 1000Base-T as many people believe.  

Cat6 was developed for the 1000Base-TX (TIA/EIA-854) standard.  Both
standards use all four pairs in the cables, but each employs a different
transmission technique and bit rate -- 802.3ab (1000Base-T) calls for a
250 Mbits/sec bit rate applied bi-directionally on each of the four
pairs, in full duplex; TIA/EIA-854 (1000Base-TX) calls for a 500
Mbits/sec bit rate applied unidirectionally on each pair so that the
transmit path is physically separated from the receive path.  Originally
the use of hybrids (separates the send/receive signal) in the 1000Base-T
chipsets made them very expensive, but the reduced cost of the
1000Base-TX chipsets did not offset the increased cabling cost for Cat6
installations, so 1000Base-TX never really caught on.

The next copper standard we have to worry about is 10GBase-T (802.3an),
which requires Cat6A or Cat7 for distances of 100 meters.  While
10GBase-T can technically utilize Cat6, it only supports distances of 55
meters.  Looking at the specifications, Cat6 doesn't really get you much
in comparison to Cat5e.  You might as well go with Cat6A or Cat7 if
you're going to future-proof your installation, so at least you'll be
good through 802.3an.  Or even better, utilize Cat5e now for your
1000Base-T connections, and use fiber for 10Gbit and beyond.

 ~ Jason A.

______________________________________________

VC3 Inc.
Senior Engineer