[K12OSN] OT: parallel running cat5e to switches

Rob Owens rowens at ptd.net
Sat Feb 21 23:09:37 UTC 2009

I'm pretty sure that network communications over ethernet only use 2 pairs of wires.  There are 4 pairs in Cat5 / Cat5e.  The extra pairs are reserved for power over ethernet, and possibly other uses.  If all this is true (I'm pretty sure it is, but you should double-check), you could conceivably use your existing wiring and be creative with the terminations so that you get "2 in 1" Cat 5 cable.

Just something to think about.  I personally consider this a not-so-great idea, although it should work.  But breaking the standard is likely to cause confusion somewhere down the line.


On Sat, Feb 21, 2009 at 08:18:45AM -0600, Barry R Cisna wrote:
> Hello List,
> Has anyone here done any real 'bean counting' studies in regards to how
> much,if any gains can be had by parallel running cat5e's from switch to
> switch. In other words running two cat5e's from say the server room
> switch to a room that gets heavy video use? This would be to use our
> existing hardware/switches .We currently have GIGE backbone with uplink
> ports at each 'hallway' switch,from there going into each class room is
> fed with 10/100 ports. I am guessing bottom line the throughput gain
> would be very marginal for all the work involved.Also trying to figure
> out if we was to do this how to conglomerate the second wire with only
> two uplink ports for each switch? (The second port on each switch feeds
> down to the next hallway switch).Not all homerun cat5 runs here:(
> We are fed with one T1 line and a second dsl for teaches/office people's
> pc's.
> We have two classrooms that are physically 600ft from the server room
> but goes through one 'junction hallway' switch so distance is still
> within reason,but you might know these are the two most used computer
> labs and sometimes i get complaints of 'being  slow'.
> Just wondering if anyone on list here has done this,and if so,if it was
> worth the trouble?
> I have Googled and cant not find any graphs,or anything to document
> this. Seems odd?
> Thanks,
> Barry Cisna
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