tbf for volume control

[Jörn Engel <joern@wohnheim.fh-wedel.de>]

Hi!

I am looking for useful information on a volume control with a token bucket
filter (see background) and am stuck. The does not seem to be much
documentation on QoS in general and about none about tbf in particular. Has
onyone ever tried tbf and can give me any hints?

Thanks!

Jörn

Background: My university is connected to the internet with 2MBit but the
ISP, the German DFN, imposes a volume limit of 80GB/month, which is roughly
250kbit on average. If the limit is exceeded, the DFN gives us the option to
buy the next catrgory with 160GB/month or to cut our wire once the limit is
reached. With a tight budget, none if these is desireable.
A bandwidth control on our side is possible and trivial, but bandwidth is
not volume.
For a volume control, the options are a BSD box with dummynet (bandwidth
control) plus a script to calculate volume usage and trim the bandwidth or a
linux box with tbf.