[LARTC] Shaping and accounting

[Rens Houben <shadur@systemec.nl>]

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Hello,

	A while ago now I had to set up a traffic shaper for the ISP I work
for, and I used linux and cbq.init to accomplish this. It worked
reasonably well, too, but after a while and some double-checking it
turned out that the ipac accounting on the same machine was consistently
reporting higher usage than was actually the case by roughly the same
factor (not amount) for every client.

	After a lot of thinking about this, the only conclusion I could reach
that didn't involve a gross and so far completely undiscovered
programming flaw in ipac or TCP/IP gremlins was that the difference was
caused by traffic shaping occuring at the point where packets exit the
machine while ipac does its accounting of packets at the point where
they enter.

	Am I right, or am I just blowing smoke and moondust, and in either
case, is there any way to correctly shape and account traffic on one
machine?

Thanks,
-- 
Rens Houben                           |    opinions are mine
Resident linux guru and sysadmin      | if my employers have one
Systemec Internet Services.           |they'll tell you themselves
PGP public key at http://suzaku.systemec.nl/shadur.key.asc  -- new Dec
12 2001

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