[101697] in North American Network Operators' Group
RE: FW: ISPs slowing P2P traffic...
daemon@ATHENA.MIT.EDU (Frank Bulk)
Tue Jan 15 19:00:48 2008
Reply-To: <frnkblk@iname.com>
From: "Frank Bulk" <frnkblk@iname.com>
To: "'Mikael Abrahamsson'" <swmike@swm.pp.se>, <nanog@merit.edu>
In-Reply-To: <alpine.DEB.1.00.0801160039230.12490@uplift.swm.pp.se>
Date: Tue, 15 Jan 2008 17:57:43 -0600
Errors-To: owner-nanog@merit.edu
Except that upstreams are not at 27 Mbps
(http://i.cmpnet.com/commsdesign/csd/2002/jun02/imedia-fig1.gif show that
you would be using 32 QAM at 6.4 MHz). The majority of MSOs are at 16-QAM
at 3.2 MHz, which is about 10 Mbps. We just took over two systems that were
at QPSK at 3.2 Mbps, which is about 5 Mbps.
And upstreams are usually sized not to be more than 250 users per upstream
port. So that would be a 10:1 oversubscription on upstream, not too bad, by
my reckoning. The 1000 you are thinking of is probably 1000 users per
downstream power, and there is a usually a 1:4 to 1:6 ratio of downstream to
upstream ports.
Frank
-----Original Message-----
From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of
Mikael Abrahamsson
Sent: Tuesday, January 15, 2008 5:41 PM
To: nanog@merit.edu
Subject: RE: FW: ISPs slowing P2P traffic...
On Tue, 15 Jan 2008, Frank Bulk wrote:
> I'm not aware of MSOs configuring their upstreams to attain rates for 9
and
> 27 Mbps for version 1 and 2, respectively. The numbers you quote are the
> theoretical max, not the deployed values.
But with 1000 users on a segment, don't these share the 27 megabit/s for
v2, even though they are configured to only be able to use 384kilobit/s
peak individually?
--
Mikael Abrahamsson email: swmike@swm.pp.se
