"Ivor Jones" wrote:
wrote in message


[snip]

: : I've seen cables, including CAT5, with both twisting
: : _and_ shielding around the whole cable assembly. I
: : don't know how much the effectiveness works together.
: : I have not had a case where I would consider using it.

That's STP (shielded twisted pair) and is not really worth it for most
applications. There is a military spec. for it somewhere, I believe.

It's also a different impedance to UTP so may not work correctly with all
equipment.

All outside plant telephone cable with the exception of
the local drop cable is shielded. Inside a telephone
office equipment room, T1 and higher speed data cables
are all shielded if the cable extends between rows or
for more distance in one row than 4 racks.

STP is significantly expensive, and will not commonly be
seen anywhere that it is not absolutely required. For
example, it would make no sense to use it within a
normal customer premise area, unless there is an
equipment room with multiple rows of equipment racks.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)