Re: [dpdk-users] AF_PACKET pmd and linux networking stack

[Andrew Wang <andrw.wng@gmail.com>]

Rami

Thank you for the suggestion. Later I found it was a problem with the dpdk
app (setting incorrect mac address).

Andrew

On Fri, Aug 17, 2018 at 5:15 PM Rami Rosen <roszenrami@gmail.com> wrote:

> Hi Andrew,
> I am not sure at all that there is a way of achieving it, because of the
> way AF_PACKET works.
> But couldn't you achieve your goal with running DPDK L2FWD or DPDK L3FWD
> application ? In such a case, when not working in promiscuous mode, it
> seems that this will avoid processing of the packets by the kernel. See the
> l2fwd and l3fwd sections in DPDK samples guide.
>
> Regards,
> Rami Rosen
>
>
>
> בתאריך יום ד׳, 8 באוג׳ 2018, 19:57, מאת Andrew Wang ‏<andrw.wng@gmail.com
> >:
>
>> Hi
>>
>> Is there a way of preventing the linux kernel networking stack from
>> handling packets when using the AF_PACKET pmd?
>>
>> Our DPDK app is running on a node that is attracting traffic for a VIP and
>> for which it has a blackhole routing rule (to drop all the incoming
>> packets
>> for that VIP).
>>
>> The intention was to have our DPDK app (running on AF_PACKET pmd for now -
>> we're still developing the app) grab those packets, process and send them
>> out (with a different address).
>>
>> Right now we can actually see those packets in our dpdk app, we process
>> them, give them a different address, but it seems that the linux kernel
>> networking stack is still dropping them.
>>
>> When the blackhole rule is removed we see the outgoing packet with correct
>> header, but also a destination unreachable message is sent out, suggesting
>> the kernel is also handling the packet. We see the same behavior when
>> using
>> iptables to drop packets (instead of blackhole route).
>>
>> Any suggestions appreciated.
>>
>> Thanks
>> Andrew
>>
>