On Mon, Sep 19, 2016 at 8:53 AM, Balazs Nemeth
<balazs.nem...@ericsson.com> wrote:
> Dear All,
> I think we found a bug in OVS master. In the test case 3 OVS is used, VXLAN
> tunnels are configured among them in full mesh, so every node has 2 Tunnel
> End Point (TEP). BFD is turned on for monitoring the tunnel liveness. In the
> beginning, traffic and BFD messages are ongoing between all the nodes. If
> you delete 1 TEP from node-1 (TEP13 towards node-3), then the remaining TEP
> on node-1 (TEP12 towards node-2) will be affected also. I expect it to work
> after deleting another TEP, but it does not transmit packets. It will not be
> able to terminate VXLAN encapsulated packets any more! Due to this the BFD
> Forwarding status of the remaining TEP will go to False, and traffic will be
> dropped between this TEP and the another TEP of this remaining tunnel. I
> also see that dpctl flows for remaining tunnel will disappear after 10 sec.
> I think when you delete one TEP from the two, some data or setting of the
> remaining TEP will be overwritten improperly. Due to RFC 7348, OVS will
> accept VXLAN encapsulated packets on UDP dst_port 4789 by default. Perhaps
> this dst_port value will be overwritten. I made a port-mirroring on the
> physical interface and I can see packets like:
> d6:ee:ac:b9:6c:81 > 00:23:20:00:00:01, ethertype IPv4 (0x0800), length 66:
> > BFDv1, Control, State Down, Flags:
> [none], length: 24
> a0:36:9f:43:f2:f8 > a0:36:9f:43:f3:d8, ethertype IPv4 (0x0800), length 144:
> > ICMP udp port 4789 unreachable, length
> 110
> The issue can be fixed if you change any parameter of the remaining TEP.
> After that TEP maybe reinitialized, and traffic can go through (BFD
> Forwarding will be True again), e.g. chaging remote_ip to random value and
> back:
> 1.       node-1: ovs-vsctl set Interface TEP12
> options:remote_ip=
> node-1: ovs-vsctl set Interface TEP12 options:remote_ip=
> The issue can be fixed also e.g. with modifying dst_port of TEPs between
> node-1 and node-2:
> 2.  node-1: ovs-vsctl set Interface TEP12 options:dst_port=4790
> node-2: ovs-vsctl set Interface TEP21 options:dst_port=4790
> We are working on the fix, any help or tips would be appreciated.

I agree it sounds like a bug :)

I haven't heard of this before, so I don't have any specific tips.
We'll look forward to seeing the patch.
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