[ovs-discuss] Issues with ARP across hosts connected with GRE tunnel

[Gurucharan Shetty]

On Mon, Jul 14, 2014 at 5:23 PM, Shridhar Sahukar
<shridhar.sahukar at cyaninc.com> wrote:
> Thanks for the response Gurucharan
>
> I dont have any issues with the routing table entries. As mentioned, after
> setting up the tunnel, if I cannot ping from br0 -> br1, and at that time,
> if I initiate a ping in the reverse direction, i.e. from br1->br0 (which
> works), everything starts working. On tcpdump, I have observed the ARP
> requests making it to the eth0 on the other host, but the same request is
> not seen on the bridge, and neither do I see the response.

What happens when both of the hosts are in the same subnet? Does a ping work?

>
> Thanks,
> Shridhar
>
>
> On Mon, Jul 14, 2014 at 4:54 PM, Gurucharan Shetty <shettyg at nicira.com>
> wrote:
>>
>> On Mon, Jul 14, 2014 at 4:22 PM, Shridhar Sahukar
>> <shridhar.sahukar at cyaninc.com> wrote:
>> > Hi,
>> >
>> > On my setup, I have 2 hosts connected with a GRE tunnel with following
>> > configuration:
>> >
>> > Host 1:
>> >
>> > #ovs-vsctl add-br br0
>> > #ifconfig br0 1.1.1.1
>> > #ovs-vsctl add-port br0 gre0 -- set interface gre0 type=gre
>> > options:remote_ip=<eth0 ip of host2>
>> >
>> > Host 2:
>> > #ovs-vsctl add-br br1
>> > #ifconfig br1 1.1.2.1
>> > #ovs-vsctl add-port br1 gre0 -- set interface gre0 type=gre
>> > options:remote_ip=<eth0 ip of host1>
>>
>> >
>> > As you can see, bridge 0 on host-1 and bridge 1 on host-2 are in
>> > different
>> > subnet and I am trying to connect them with a GRE tunnel.
>> I suppose you have set the netmask properly. Otherwise they are in the
>> same subnet.
>> Assuming they are in different subnet, you will probably need routing
>> table entries.
>>
>>
>> >
>> > This setup works as expected for all other purposes, except that during
>> > the
>> > initial setup the ARP communication does not happen as expected.
>> >
>> > Most of the times, when we ping bridge0 IP from host2 or bridge1 IP from
>> > host1, the ping does not work. tcpdump on the eth0 interface shows
>> > incoming
>> > ARP requests, but I dont see any ARP responses going back. At this
>> > point, if
>> > I initiate a reverse ping then everything starts working.
>> >
>> > It seems that the ARP requests are not getting forwarded to the bridge
>> > from
>> > the GRE interface. Do I need to add any special flow?
>> >
>> > Any help is much appreciated.
>> >
>> > Thanks,
>> > Shridhar
>> >
>> >
>> > _______________________________________________
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>> > discuss at openvswitch.org
>> > http://openvswitch.org/mailman/listinfo/discuss
>> >
>
>