Re: CLASSIFY target

[Patrick McHardy <kaber@trash.net>]

Eliot, Wireless and Server Administrator, Great Lakes Internet wrote:
> I am attempting to classify packets in tc using the iptables classify
> target in the postrouting chain of the mangle table, but it does not
> work. I am looking through the code to try to find out what is going on
> (whether I am doing something wrong, or whether the kernel module code
> is messed up). I have verified that the ipt_CLASSIFY.c file is correctly
> building a handle and that it is storing the handle in the skb->priority
> field. However, inside the packet scheduler code, I cannot find where
> the skb->priority field is being read so that the packets can be sent to
> the correct class. Could someone please point me in the correct
> direction for viewing this section of the code? Thanks.


The *_classify functions of the individual schedulers use it. I see
you also posted a more detailed description of your problem to lartc:
you can't use classify to classify to multiple nested qdiscs. So
if you have something like:

         <1:0 (root) hfsc>
<1:1 hfsc class> <1:2 hfsc class>
         |
   <2:0 PRIO>
         |
<2:1 - 2:3 PRIO classes>


and say CLASSIFY --set-class 2:1, the upper HFSC qdisc had no idea
how to reach qdisc 2:0. You can either use CLASSIFY --class 2:0
and then attach more classifiers to the PRIO qdisc or manually
direct traffic from 1:0 -> 2:0 and use CLASSIFY --set-class 2:1.
CLASSIFY is really only useful if you have only a single level
of classful qdiscs.