Re: Problem using tc-sfq with tc-flow for arbitrary hashing

Carmelo Cascone wrote:
> Hi all,
>
> I have a problem in configuring tc-sfq along with tc-flow. I would like to hash packets not using the UDP/TCP 5-tuple (default beahvior of tc-sfq), but simply the pair <ipsrc, ipdst>. I’m having hard time using tc-flow and finding help on the web, as such I decided to drop an email to this list.
>
> The commands and error I get are:
>
> $ tc qdisc add dev eth6 root handle 1: sfq
> $ tc filter add dev eth6 parent 1:0 protocol ip prio 1 flow hash keys src,dst perturb 30 divisor 1024
> RTNETLINK answers: Invalid argument
> We have an error talking to the kernel
>
> I’m issuing these commands on a Debian 9 with a kernel v4.9.16
> Please note that the tc filter command is the same used in the tc-sfq documentation.
>
> What am I doing wrong? What is the invalid argument?

Looking through many years old Qos folder I found a file with an example.

I don't know why it's not documented, but but adding handle 1 to the
filter command makes your example work for me, in the sense that it's
not rejected - didn't test further.

Historically I would have said putting sfq on root of an eth wouldn't
do much, but with BQLs maybe things have changed.