[ovs-discuss] Replacing IPsec-GRE tunnel ports

Bolesław Tokarski boleslaw.tokarski at gmail.com
Wed Nov 23 08:29:01 UTC 2016


Hi,

I would love this to be a problem of the testing tool. It does not seem to
be the case, though. I ran iperf3 in the default mode, which is TCP, and it
was the same command tested on OVS with VLAN tagging and without it - it
achieved 870Mbps without VLANs.

Ansis, your wireshark suggestion was in the right direction - although I
did test outgoing packets with tcpdump already, but these were ESP, so not
saying a lot. Now I made a test of the traffic flowing through the internal
interface, and indeed there's some weird going on.

The untagged traffic was a smooth flow of TCP sends and ACKs, the tagged
traffic is more interesting. I get a significant number of losses,
retransmissions, TCP out-of-order notes, there's even an RST near the end.
Packets are marked as 'don't fragment'. MTU on the interface is 1394,
raising it to 1420 makes the traffic flatten out to 0, lowering it does not
seem to make a difference.

I am attaching the packet dump from the capped communication, the non-VLAN
comms produced 200MB packet capture during the same 2s, so not that sexy to
transfer over email.

I am trying to bring up two Ubuntu 15.04 VMs, this version has OVS 2.3.2,
but an older kernel, 3.19, I'll try to see on which other environment I can
or can not reproduce the problem. I'm afraid I'm not capable enough to
dismantle the kernel and see which code path does one traffic go through
and the other does not.

Best regards,
Bolesław Tokarski
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