[138268] in North American Network Operators' Group
RE: What vexes VoIP users?
daemon@ATHENA.MIT.EDU (Frank Bulk)
Wed Mar 2 00:55:21 2011
From: "Frank Bulk" <frnkblk@iname.com>
To: "'Scott Helms'" <khelms@ispalliance.net>,
<nanog@nanog.org>
In-Reply-To: <4D6D0402.7020404@ispalliance.net>
Date: Tue, 1 Mar 2011 23:55:16 -0600
Reply-To: frnkblk@iname.com
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Scott:
Are you saying that the large MSOs don't use CM configuration files that =
create separate downstream and upstream service flows for Internet, =
voice signaling, and voice bearer traffic? =20
Frank
-----Original Message-----
From: Scott Helms [mailto:khelms@ispalliance.net]=20
Sent: Tuesday, March 01, 2011 8:35 AM
To: nanog@nanog.org
Subject: Re: What vexes VoIP users?
offered through the various broadband providers I have had.
> 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.
>
No, this incorrect. Packet Cable most certainly _is_ VOIP (a MGCP=20
variant to be precise until 2.0 after which it is SIP). While a few=20
providers, usually for non-technical reasons, did deploy an entirely=20
separate set of downstream and upstream interfaces that is far from the=20
norm. AFAIK the only top 20 MSO to do so in scale was Charter and I=20
don't know if they continue that today. Comcast, the largest cable=20
telephone provider certainly does not nor do providers need to since any =
Packetcable CMTS and EMTA combo offers reliable prioritization in the=20
same channel(s) as the normal data path.
> So of course Vonage and other VoN products will be less rugged.
>
> 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".)
As I said, this second channel doesn't exist in almost all cases (its=20
not cost effective nor needed in almost all cases). Having said that=20
over the top VOIP providers do suffer in comparison because they don't=20
get the benefit of prioritization in the local cable plant.
> Cheers,
> -- jra
>
>
--=20
Scott Helms
Vice President of Technology
ISP Alliance, Inc. DBA ZCorum
(678) 507-5000
--------------------------------
http://twitter.com/kscotthelms
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