DPDK server packets with AF_PACKET driver are not received by the client connected to the same virtual bridge.

[Boris Ouretskey <borisusun@gmail.com>]

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Hi

I am trying to run a docker based system in one VM, with some servers using
the DPDK and facing a very strange issue.

The relevant part of the system is the echo server which is built with DPDK
library and runs in docker, connected to the virtual bridge (with AF_PACKET
driver), and echo client built with regular sockets (java application). See
the drawing below for visual details.

The strange thing is that echo replies sent from DPDK echo server docker
(Docker2), can be seen in tcpdump in the docker of echo client (Docker1)
however the application (java client) does not receive it on socket level.
When the echo server runs as a socket application everything works. Seams
like OS (linux) decide not to route the packet to the application for
some reason.

Some quick important notes.

- DPDK layer starts ok and no EAL errors are reported. Its echo replies as
mentioned before can clearly be seen when capturing traffic on eth0 in
client docker.
- It is not the issue of parsing the echo replies on application level. I
checked the strace logs and cannot see any traffic delivered to the
application
- I have compared the captures from working socket based echo server and
MACs seam to be ok, also the packets sent from DPDK server are formed well.
- No logs for martian packets when enabled.

I would like to focus the attention of dear DPDK experts on the following
question: is it possible that DPDK AF_PACKET driver intercepts both packets
destined to  the virtual nic eth0 of Docker1 AND eth0 of Docker2,
preventing it from being received by application?

DPDK Version 18

VIRTUAL BOX VM (Alma Linux)

    Docker1                                 Docker2
+---------------+                       +------------+
|               |    Request            |            |
|               |   -------------->     |  DPDK      |
| Socket Echo   |                       |  Echo Server
|   Client      |         Reply         |  Server    |
|               |   <-------------      |            |
--vdev=eth_af_packet0,iface=eth0,qdisc_bypass=1
|               |                       |            |
|          tcpdump -i eth0              +------+-----+
+-------+-------+                       eth0   |
        | eth0                                 |
        |                               No IP  |
 +------v--------------------------------------v-----+
 |             Virtual Docker Bridge                 |
 +---------------------------------------------------+


Thanks

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