[VoIP] CAT6 Cable

[Joe Koberg]

Shane Young wrote:
> I don't know about cat6, but we used to put in 25pr cat5 stuff all the time.
>
> I'm not sure what your application is that requires cat6, keeping in  
> mind that ethernet is lmited to 100 meters (about 328 feet).
>   
> With that in mind, you don't have much room left to run cables from  
> your termination points on each end out to workstations.
>   


Modern ethernet connected to full-duplex ports on both ends works pretty 
well even for quite long runs. If you force the adapters or switches to 
100mbit it may perform better (or maybe worse because gigabit uses 
advanced signal coding). The key is that it must be full-duplex to avoid 
the timing issues associated with two nodes far apart. The ethernet 
network "diameter" was historically limited by signal timing, not signal 
quality.

I have certainly linked two buildings at gigabit speeds with a run of 
cat6 in an underground conduit.  I would be more careful with aerial 
runs. Some might worry about ground loops or static issues, but ethernet 
is transformer-coupled so the ground loops aren't an issue. I also used 
a cheap gigabit switch at each end as a "ESD protector".... i dont mind 
replacing a $50 switch if it gets hit by static discharge. However they 
are still going after several years. The run is probably 150 yards.

When the phone company does it, they use gel-filled underground-rated 
cable, sometimes with a kevlar jacket to prevent cuts. They also 
terminate each end on grounded lightning protectors at the building 
entrance. This is probably required by building codes.


Joe Koberg
joe at osoft dot us