Re: QoS on incoming data

[Christopher E. Brown]

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.