What vexes VoIP users?

Scott Helms khelms at ispalliance.net
Wed Mar 2 09:21:46 CST 2011

>> As I said, this second channel doesn't exist in almost all cases (its
>> not cost effective nor needed in almost all cases). Having said that
>> over the top VOIP providers do suffer in comparison because they don't
>> get the benefit of prioritization in the local cable plant.
> "Cost-effective"?
> Could you expand on how the provisioning of a second virtual pipe down
> the hill to a cable box has any incremental costs at all?
> Cheers,
> -- jra

Because it takes either another 6 MHz on the downstream side that could 
be used for a TV channel as well as 3.2 MHz (or 6.4 MHz for >=D2) on the 
upstream side.  It also takes the CMTS interfaces, which are not cheap 
even with the advent of high capacity cards & QAMs for D3.  On top of 
all this it also takes more time on the design and management side 
because you have to make sure all of your nodes are getting both sets of 
channels and you have to make sure your provisioning or CMTS config 
keeps the EMTA's on the right channels.

Scott Helms
Vice President of Technology
ISP Alliance, Inc. DBA ZCorum
(678) 507-5000

More information about the NANOG mailing list