----- Original Message -----
From: "Michael Thomas" <mike@mtcc.com>
On 03/01/2011 05:51 AM, Jay Ashworth wrote:
Let us be clear: if you're getting "digital telephone" service from a cable television provider, it is *not* "VoIP", in the usage in which most speakers mean that term -- "Voice Over Internet" is what they should be saying, and cable-phone isn't that; the voice traffic rides over a separate DOCSiS channel, protected from both the Internet and CATV traffic on the link.
Er, I'm not sure what the difference you're trying to make.
Er, I'm not sure why...
Is IP running over an L2 with a SLA any less "IP" than one without a SLA? That's all the DOCSIS qos is: dynamically creating/tearing down enhanced L2 qos channels for rtp to run over. It's been quite a while since I've been involved, but what we were working on with CableLabs certainly was VoIP in every respect I can think of.
Wow. I thought I was pretty clear in what I said above; I'm sorry you didn't get it. "What everyone is actually *selling* commercially, except for cable providers, is *not* VoIP; it's a subset of that: VoN; Voice Over Internet; where the IP transport *goes over the public internet*, and through whatever exchange points may be necessary to get from you to the provider. Cable companies are selling you *one hop* (maybe 2 or 3; certainly not 12-18), over a link with bandwidth protected from whatever may be going on on the Internet IP link they're also selling you; and which is therefore guaranteed to have better quality than whatever "VoIP" service it might be competing with." Better?
| As I recall, this questionably fair competitive advantage has been
looked into by ... someone. (Cablecos won't permit competing VoIP services to utilize this protected channel, somewhere between "generally" and "ever".)
There's is a great deal of overhead involved with the booking of resources for enhanced qos -- one big problem is that it adds quite a bit of latency to call set up. I'm sceptical at this point that it makes much difference for voice quality since voice traffic is such a tiny proportion of traffic in general -- a lot has changed in the last 15 years. Now video... I'm willing to believe that that enhanced qos still makes a difference there, but with youtube, netflix, etc, etc the genie isn't getting back in that bottle any time soon. So Moore's law is likely to have the final word there too making all of the docsis qos stuff ultimately irrelevant.
I wasn't suggesting QOS. I was suggesting *there's a completely separate pipe*, on non-Internet connected IP transport, carrying only the voice traffic, directly to a termination point, which is dedicated from the triple-play box and nailed up. Are you suggesting that's *not* how it's being done in production? Cheers, -- jra