[LARTC] Q about "overlimit", and IMQ/NAT trick

[cm@tahina.priv.at (christian mock)]

hi,

I've successfully implemented shaping and policing with HTB for my
SDSL line. 

Some tips&tricks I discovered which were not covered in the FAQs and
docs I read:

- To discover the appropriate rate for your line, flood it with
  traffic and reduce the rate until the matching class starts to show
  a consistent backlog -- only then you've managed to take the queue
  away from your modems/routers and into the shaping box.

- The docs only speak about the IMQ device in connection with the
  PREROUTING chain -- the problem is that at that point, incoming
  packets are not de-masqueraded yet, so you can't fwmark and shape
  depending on the internal address; I use

  <iptables packet marking>
  iptables -i $EXT_IF -A FORWARD -t mangle -j IMQ

  without problems.

Questions:

I'm not quite sure if I shoot myself in the foot with that IMQ setup
-- packets get stuffed into the IMQ device from the mangle table, but
where and how do they "reappear" after shaping?

The other question that remains is: with "tc qdisc show", I see
overlimit!=0 only for the root qdisc -- I would have expected it to
increase on the queues or classes where actual rate > configured
rate... why is that?

ciao,

cm.

-- 
Actually, I found New Zealanders to be the most akin to Canadians.
They also feel the looming presense of a next door neighbour country
full of loud, excessively happy and somewhat simple people, and are a
little intimidated by it. -- Paul Tomblin
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