[LARTC] Re: how flexible is ingress traffic policing to bandwidth limit?

[Greg Stark <gsstark@mit.edu>]

Damion de Soto <damion@snapgear.com> writes:

> You can create different ingress policers that only match specific ports, and
> give them different priorities, but that still won't work as well as using IMQ,
> or if your box is a gateway (and you are only shaping traffic going through it),
> then you can use egress queues on the LAN interface.

For some reason that hadn't occurred to me. That should work just fine. I
guess I should mark the packets in iptables to avoid throttling traffic from
gateway itself, or does match see the external ip?

IMQ does seem like a handy tool, but why is there a distinction at all between
egress and ingress qdiscs at all? Why not just allow people to attach HTB as
an ingress qdisc directly?


I suppose in an ideal world the best thing would be to receive the packets,
hand them to user-space, but not mark them as received, ie, not ack them. That
avoids introducing any loss from the user point of view but still slows the
flow down. But that seems fiddly and would only work for TCP I guess.

-- 
greg

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