[100256] in North American Network Operators' Group
Re: Comcast blocking p2p uploads
daemon@ATHENA.MIT.EDU (Sean Figgins)
Fri Oct 19 23:44:12 2007
Date: Fri, 19 Oct 2007 21:43:05 -0600
From: Sean Figgins <sean@labrats.us>
To: nanog@nanog.org
In-Reply-To: <!&!AAAAAAAAAAAuAAAAAAAAAKTyXRN5/+lGvU59a+P7CFMBAN6gY+ZG84BMpVQcAbDh1IQAAAATbSgAABAAAACaJvLu3TXUTrYkNySI8KsJAQAAAAA=@iname.com>
Errors-To: owner-nanog@merit.edu
Frank Bulk wrote:
> 2) DSL and fiber have limitations, too. The modulation and spectrum width
> can vary, but most MSOs have their forward configured with a maximum of
> around 38 Mbps (256-QAM, 6 MHz wide) and the return in the 9 Mbps range
> (64-QAM, 3.2 MHz wide). Charts here:
> Forward: http://www.cable360.net/images/articles/15131_1168455349.gif
> Return: http://www.cable360.net/images/articles/15131_1168455396.gif
Thank you, Frank. I'm not a HFC engineer, but rather an
IP/Network/Server/Security guy, that worked on the backbone and lab side
of a large MSO. My HFC experience is exclusive of what is between the
CMTS and the cable modem. I know just enough to be able to live there.
I got my figures reversed. For some reason I was thinking that it was
about 100 meg on the upstream and 45 meg on the downstream, but looks
like I remembered it wrong.
Anyways, regardless of that, you pretty much validated what I was saying
as to the reason why a MSO would deploy such a device. It's possibly
cheaper to do so than to deploy the hardware to split the HFC pland and
increase available bandwidth to subscriber ratio. Not that I agree with
such a practice.
-Sean