Re: Are there any alternatives to IFB for downlink shaping?

[Andy Furniss <adf.lists@gmail.com>]

Nick Pelling wrote:

> I was hoping (of course) that IFB would be able to do this for me,
> but it doesn't seem to want to play nicely. Am I missing something?
> All suggestions and comments very much appreciated! :-)

I think IFB should do here, Andrew already mentioned IMQ, but for normal
setups the only real need for that would be if you need to shape traffic
destined for the router as well as forwarded and then only if you have
to nat onto a single public address. Your setup seems to be just
forwarding so that doesn't apply.

You should be able to use ifb to catch traffic leaving on the lan facing
egress devices. Having previously marked using iptables
depending on dst if or mark with tc.

To use filters to redirect from both br0 and wl1 to a single ifb you
will need to add eg, a prio qdisc to br0 and wl1 (just because you can't
add filters to a device without a "real" qdisc on it, the default
pfifo_fast will not do).

One other thing to remember is that shaping traffic coming in from wan
is not the same as shaping that going out - you are at the wrong end of
the bottleneck and have to back off/sacrifice some bandwidth or you will
never build up a queue to do anything with. How much to back off
somewhat depends on the speed of the link and how much you care about
latency and how hard you hit the line eg shaping a few tcps is easier
than a few hundred from torrents.