Updates using idle bandwidth

[Bruno Wolff III]

On Tue, Mar 04, 2008 at 15:32:41 -0500,
  Sunil Ghai <sunilkrghai at gmail.com> wrote:
> >problem is you need to decide what 40% of 'the bandwidth' actually is, and
> >in general you do not know that if you're not paying attention to what
> maximum
> >has been achieved.  Anything else is a guess.  If you really want users to
> feel
> >like all their extra bandwidth is getting used without interfering with
> traffic
> >they want to move you cannot guess there, because tcp will back down on
> both
> >connections as soon as it detects congestion if they aren't prioritized.
>  You
> >would need a mechanism to remember how fast a user's connection really is.
> 
> Yep, setting priority is necessary otherwise the solution will not work and
> I think I'll face more problems while implementing but I want to work on
> this because me and many people have been facing the same problem for a long
> time. Just waiting to get over with my university exams, then I'll start
> working, perhaps through Google Summer of Code..

You might take at the LARTC Howto. It describes ways to can allocate
bandwidth to different things in a way that doesn't force you to not
waste bandwidth if some things don't need it. However for this to work
well you do need some way to estimate what the capacity of the link
is. Also controlling inbound traffic is hard since you can't directly
stop people from sending stuff to you and excess traffic will be dropped
on the other side of the link which isn't under your control.
This would be useful for other things besides updates. Being able to
prioritize interactive traffic over bulk traffic is something a fair
number of people have use for.
When you are looking at the LARTC Howto, note that it is a bit out of
date. IFB interfaces replace IMQ interfaces and there isn't a lot of
documentation on them.