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Is there a minimum length for a patch cable? I think I found somewhere a
text saying that the limit is 3 ft, but for the life in me I can't find the
reference

Thanks
SP

Sparanghel wrote:

Is there a minimum length for a patch cable? I think I found somewhere a
text saying that the limit is 3 ft, but for the life in me I can't find the
reference

Thanks
SP

I've seen them as short as a couple of inches. worked fine.

--Dale

Dale Farmer <dale@cybercom.net> wrote:

I've seen them as short as a couple of inches. worked fine.

I've made them 6 cm wirelength to cross over two interfaces in
the same machine. Ran fine. This is far more demanding than the
typical patch panel that has 100's of feet of total wirerun.

My shortest is a single loopback plug. 2 cm wire. Also works fine.

-- Robert

"Robert Redelmeier" <redelm@ev1.net.invalid> wrote in message
news:331%e.1839$rl1.1319@newssvr27.news.prodigy.net...

Dale Farmer <dale@cybercom.net> wrote:
I've seen them as short as a couple of inches. worked fine.

I've made them 6 cm wirelength to cross over two interfaces in
the same machine. Ran fine. This is far more demanding than the
typical patch panel that has 100's of feet of total wirerun.

My shortest is a single loopback plug. 2 cm wire. Also works fine.

-- Robert

Finally I found the reference. Is not very conclusive:

http://www.ertyu.org/~steven_nikkel/ethernetcables.html


Remember, an end to end connection should extend at least 1m (3ft) and not
more than 100m (~328ft). Yes, there is a minimum, its little known, little
referred to and not usually important, but I have seen cases where short
cables caused problems. The longer the cable becomes the more it may affect
performance, usually it is a gradual decrease in speed and increase in
latency. When uplinking between (cascading) hubs/switches, you usually need
a very short cable, less than 1m, check the device's specifications.
SP

Sparanghel <SParangell@aol.com> wrote:

Finally I found the reference. Is not very conclusive:

http://www.ertyu.org/~steven_nikkel/ethernetcables.html


Remember, an end to end connection should extend at least
1m (3ft) and not more than 100m (~328ft). Yes, there is
a minimum, its little known, little referred to and not
usually important, but I have seen cases where short cables
caused problems. The longer the cable becomes the more it
may affect performance, usually it is a gradual decrease
in speed and increase in latency. When uplinking between
(cascading) hubs/switches, you usually need a very short
cable, less than 1m, check the device's specifications. SP

I'm deeply suspicious of a reference with homebrew information.

"gradual decrease in speed"? never seen. I've run overlength
cables at full wirespeed.

"increase in latency"? Only theoretically. A full 100m roundtrip
takes 0.0010 milliseconds.

Cascading 100baseTX hubs (if you can ever find one) is subject to
very tight rules to respect the collision diameter. 10baseT has
the old 5-3-1 rules. Switches aren't subject to these cascading
rules.

Perhaps the author has seen problems with short cables.
With homemade crimp-on-solid I'd expect problems.

-- Robert

Robert Redelmeier <redelm@ev1.net.invalid> wrote:

Perhaps the author has seen problems with short cables.
With homemade crimp-on-solid I'd expect problems.

Whatever the length of the cable. Though some people
just don't appear to understand why putting crimps on
solid cable is a bad idea.

--
Mark Evans
St. Peter's CofE Aided School
Phone: +44 1392 204764 X109
Fax: +44 1392 204763