[ale] OT: GigE Copper specs

[Greg Freemyer]

On Fri, 2004-04-09 at 11:32, Dow Hurst wrote:
> May I ask what is a punch down?  Is that cutting the cable and adding a RJ-45 
> connector?
> Dow
> 
You do have to count the amount of cable that was untwisted when putting
on a connector, but that is not a punch down.

Punch downs are typically used on patch-panels and first came from phone
system wiring, but they are now used in "structured wiring" for
networks.

You can buy punch down blocks and tools at Home Depot, etc..

Typically, the punchdown block has a lot of metal posts sticking out of
a pc board.  The posts are then connected together on the board:

A -- A 
B -- B
C -- C
D -- D

In the above, the left column of posts could be used for running your
room to room wiring, and the right column for running out to wall
connectors.  That way the room-to-room wiring can basically be
permanent, but you can replace your local runs if they need to be moved
for some reason.

Greg
-- 
Greg Freemyer


> 
> Greg Freemyer wrote:
> > On Wed, 2004-04-07 at 14:43, griffisb at bellsouth.net wrote:
> > 
> >>Hey all, had an off-topic question about Gigabit Ethernet specs. Is it supported on Cat 5 cable, patch panels and patch cords - or is Cat5e or better required. Distance is 100 meters, correct?
> >>
> >>I'm seeing a lot of errors on some GigE ports at work, and beleive it to be infrasture-related.
> >>
> >>_______________________________________________
> >>Ale mailing list
> >>Ale at ale.org
> >>http://www.ale.org/mailman/listinfo/ale
> > 
> > 
> > I don't know the details, but I do know that patch panel punch down
> > techniques that work for 100 Mbit don't work for GigE.
> > 
> > For instance, with 100 Mbit it was not unusual to unwind several inches
> > of individual wires near the punch downs.
> > 
> > With GigE, much tighter tolerances are needed for maintaining the
> > twisted pairs all the way to the punch down.  (For some reason I'm
> > thinking less than 6 inches of untwisted cable cummulative over the
> > end-to-end connection.  If you are using multiple punch downs, then it
> > adds up quickly.)
> > 
> > So, if you are doing punch downs (even if you have all GigE acceptable
> > components) it is easy to mis-install patch panels, etc.
> > 
> > Greg