nanog mailing list archives

Re: cross connect reliability


From: Seth Mattinen <sethm () rollernet us>
Date: Sun, 20 Sep 2009 23:48:56 -0700

Luke S Crawford wrote:
Richard A Steenbergen <ras () e-gerbil net> writes:
You've never seen a single port go bad on a switch? I can't even count
the number of times I've seen that happen. Not that I'm not suggesting 
the OP wasn't the victim of a human error like unplugging the wrong port 
and they just lied to him, that happens even more.

I know it happens;  it's happened to me, and I have probably touched fewer
switches than you.  Still, from what I can understand, it can be
prevented/minimized by the use of a grounded port.


from: 
http://support.3com.com/documents/switches/baseline/3Com-Switch-Family_Safety-Reg-Info.pdf


"CAUTION: If you want to install the Switch using a Category 5E or
Category 6 cable, 3Com recommends that you briefly connect the cable
to a grounded port before you connect to the network equipment. If you
do not, the cable’s electrostatic discharge (ESD) may damage the Switch's
port.

You can create a grounded port by connecting all wires at one end of a
UTP cable to an earth ground point, and the other end to a female RJ-45
connector located, for example, on a Switch rack or patch panel. The
RJ-45 connector is now a grounded port."



HP chassis switches ship with a grounding jack accessory you attach to
the DB9 port (I assume it ties all RJ-45 pins to shied/ground)
explicitly for this purpose. The instructions say to always plug a cable
into the grounding device before connecting to a switch port.

~Seth


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