----- Original Message ----- > From: "Michael Thomas" <m...@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
