Re: QoS on incoming data

From: Christopher E. Brown (
Date: Tue Jun 11 2002 - 15:07:53 EST

On Tue, 11 Jun 2002, DervishD wrote:

> Hi all :)
> After reading a bit of the HOWTO about traffic control and
> advanced routing, I have a doubt about the queue disciplines and
> traffic shaping.
> I've seen that, except the 'ingress' qdisc (and maybe the
> hierarchycal token bucket) all other qdisc's seem to be only valid
> for outgoing traffic, although I suppose that some of those qdisc
> could be easily applied to incoming traffic.

The ingress system is for corner cases and special situations. In
general you do not control the flows *entering* the router, but
*leaving* it.

I router or system *cannot* limit the traffic it receives, if it is
coming down the wire at you you receive it. The ingress system simply
lets you decide to discard or delay a packet before it gets passed to
the local stack.

This allows you to cover a few corner cases, such as not being in
control of the upstream router where you *must* limit traffic *to*
the local machine.

For an example 2 interface machine, you receive traffic on A and limit
its retransmission on B, you receive traffic on B and limit its
retransmission on A.

For the special case of a server that needs to limit traffic to/from
itself you use an ingress rule to throttle incoming traffic, and an
egress rule to throttle outbound. To control *any* bi-directional
flow requires at least 2 rules.

I route, therefore you are.

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This archive was generated by hypermail 2b29 : Sat Jun 15 2002 - 22:00:23 EST