Can P2P applications learn to play fair on networks?

Tue Oct 23 02:37:42 UTC 2007

With PCMM (PacketCable Multimedia,
http://www.cedmagazine.com/out-of-the-lab-into-the-wild.aspx) support it's
possible to dynamically adjust service flows, as has been done with
Comcast's "Powerboost".  There also appears to be support for flow
prioritization.

Regards,

Frank

-----Original Message-----
From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu] On Behalf Of
Mikael Abrahamsson
Sent: Monday, October 22, 2007 1:02 AM
To: nanog at merit.edu
Subject: Re: Can P2P applications learn to play fair on networks?

On Sun, 21 Oct 2007, Eric Spaeth wrote:

> They have.   Enter DOCSIS 3.0.   The problem is that the benefits of
DOCSIS
> 3.0 will only come after they've allocated more frequency space, upgraded
> their CMTS hardware, upgraded their HFC node hardware where necessary, and
> replaced subscriber modems with DOCSIS 3.0 capable versions.   On an
> optimistic timeline that's at least 18-24 months before things are going
to
> be better; the problem is things are broken _today_.

Could someone who knows DOCSIS 3.0 (perhaps these are general
DOCSIS questions) enlighten me (and others?) by responding to a few things
I have been thinking about.

Let's say cable provider is worried about aggregate upstream capacity for
each HFC node that might have a few hundred users. Do the modems support
schemes such as "everybody is guaranteed 128 kilobit/s, if there is
anything to spare, people can use it but it's marked differently in IP
PRECEDENCE and treated accordingly to the HFC node", and then carry it
into the IP aggregation layer, where packets could also be treated
differently depending on IP PREC.

This is in my mind a much better scheme (guarantee subscribers a certain
percentage of their total upstream capacity, mark their packets
differently if they burst above this), as this is general and not protocol
specific. It could of course also differentiate on packet sizes and a lot
of other factors. Bad part is that it gives the user an incentive to
"hack" their CPE to allow them to send higher speed with high priority
traffic, thus hurting their neighbors.

--
Mikael Abrahamsson    email: swmike at swm.pp.se