[ovs-discuss] OVS in userspace - forwarding traffic to the local port does not reach the application layer?

Mirza Avdic mirza.avdic at tum.de
Mon May 28 17:13:17 UTC 2018


Hi,

I have been trying to use OF1.3 metering capabilities for some time in the
OVS, and I was able to make this work by building and configuring OVS in
the user space as it is described in the official documentation.

I am building a network emulator which consists of multiple OVS switches
connected via veth-s, where each OVS is instantiated in a separate Docker
container. Each container runs also sshd and dhclient.

Running datapath in the user space seems not to be able to forward traffic
to local applications, in this case dhclient and sshd. Basically what I am
trying to do is to forward traffic intended for these 2 applications to the
logical OpenFlow LOCAL port. Flow rules are matched and I can observe the
traffic on the LOCAL port via Wireshark, but it seems that the application
layer does not receive the traffic.

My assumption is that the OVS user space implementation that uses DPDK
cannot forward traffic to the application layer, since the kernel network
stack is not used in this case.

The strange thing is that the traffic in the opposite direction is matched
and forwarded correctly, e.g. DHCP DISCOVER message, which originates from
the dhclient, is broacasted on all ports as it should be, but on the other
hand DHCP OFFER, originated from the DHCP server, cannot reach the dhclient.

Using OVS datapath in the kernel space I have not had these issues, and the
traffic is forwarded as it is programmed, but then I cannot use meters,
which I would like to use.

Can anyone more familiar with the OVS userspace implementation comment on
this issue?

Thank you!

Regards,

Mirza
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