Prioritize a vlan on another

Prioritize a vlan on another

[footplus]

Hello,

I'm not sure if this is the right place to ask this, but i'm stuck on a trafic priority problem since some time.

I have 2 10Gb interfaces (bnx2x) bonded in a 802.3ad aggregate. On this aggregate, 2 vlans are configured (let's INT and EXT) I need to ensure that, when sending traffic at near line rate via EXT, all packets targeted to INT are sent in priority (dropping EXT traffic as needed).

My devices have the mq qdisc by default (running CentOS 7, kernel 3.10).

After googling for documentation about the mq qdisc, I saw it was a stub to have one root qdisc per tx queue, so I expected that below were standard pfifo_fast qdiscs and that I should be able to just mark traffic as Minimize-Delay via iptable's TOS target, but it seems that it has no visible effect when mq+pfifo_fast are in effect.

I played with various qdiscs, and I think I got the right behavior when replacing the mq root qdisc by a prio qdisc (along with using TOS target), but then I was loosing the per-queue lock aspect of the mq qdisc. I did not manage to reproduce this with mq yet.

Could you recommend a way of achieving my goal with the maximum performance ?

Should more details be needed about my setup, i'll collect and send them.

Thanks for your help,

Best regards,
-- 
Aurélien

Re: Prioritize a vlan on another

[Aurélien]

On Tue, Sep 1, 2015 at 11:07 PM, <footplus@gmail.com> wrote:
>
> Hello,
>
> I'm not sure if this is the right place to ask this, but i'm stuck on a trafic priority problem since some time.
>
> I have 2 10Gb interfaces (bnx2x) bonded in a 802.3ad aggregate. On this aggregate, 2 vlans are configured (let's INT and EXT) I need to ensure that, when sending traffic at near line rate via EXT, all packets targeted to INT are sent in priority (dropping EXT traffic as needed).
>

Replying to myself:

It seems that all I was needing was a -j CLASSIFY --set-class 0:6 in iptables.

This sufficed to classifiy the traffic in band 0 within 8 prio qdisc
(with default priomap/bands) attached below the 8 first classes of mq.
However, the packet TOS does not seem to affect the priority inside
the VLAN/bonding with mq in any way.

Problem solved for me.

Thanks,
Best regards,

-- 
Aurélien Guillaume