North American Network Operators Group
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Re: fast ethernet limits

  • From: blitz
  • Date: Fri Jan 10 17:09:20 2003

I believe your pushing the limits as to ethernet over Cat5.
I can suggest you use the very best cable (shielded of course) you can get, and be meticulous in your connector installations and you might get away with it. Avoid other wiring if possible (fat chance huh?) and anything electrical interference producing, like fluoro ballasts, transformers etc. etc.
Ground the end closest to earth ground to a good common point ground in the building, (not a power box) and leave the other end free floating and not touching anything electrically.
100 meters is supposedly the limit for ethernet, and "assuming" a 12' floor, your'e around 24 feet over spec.
You might try to find some cat 6 cable if you can, its supposedly super premium cat 5, with better freq response and jittter control.
http://www.controlcable.com/products/category_6_cable.html

One last advice, use REAL good patch cables as well...they may help squeeze the last bit of performance out..


At 12:01 1/10/03 -0800, you wrote:

Hi NANOG,

Could someone please help me with a fast ethernet problem I am having. We
have a POP in a 27 floor building, and have a rj45 run from the the bottom
of the building (in the telco room) to the top of the building. We have
cisco switches on either end and we are seeing about 5-20% packet loss on
the trunk.

Are we running into a distance limitation of fast ethernet, or are we suffering
from another problem? I read that 328 feet is the limitation of fast
ethernet. Is there anything short of getting a repeater for the cable run
that I can do to boost the signal?

TIA for your help.

Ciao.

Steve Rude