[c-nsp] Coax question for DS3

[Jay Hennigan]

Nick Voth wrote:
> Hey guys,
> 
> I've never had to pull our own DS3 coax cable before and I'm now faced with
> it. It's no big deal, BUT in some of the Cisco documentation it recommends
> that the 2 strands of coax be bound together with shrink wrap or something
> like that. I'm using 75-ohm RG6 shielded coax with the compression type BNC
> connectors. Is it really necessary to tie the two cables together to reduce
> the effects of EMI?
> 
> Thanks very much,

I generally use WECo style 735A type cable for this as opposed to RG6. 
It is much smaller and easier to work with.  The typical RG6 one finds 
for cable TV use is rather bulky.  Try Stonewall Cable for pre-made DS-3 
jumpers with two cables in a common sheath.  There isn't an EMI issue, 
perhaps the idea of a common jacket was for cable management or to 
ensure that propagation delay and attenuation in both directions is 
similar.  Unless you are dealing with a very long run, RG6 is not 
needed.  Some Cisco gear actually performs better with lower signal 
levels.  Often a pad is needed to knock down a hot signal.

--
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
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