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

[Shridhar Sahukar]

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.

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
> >
> >
> > _______________________________________________
> > discuss mailing list
> > discuss at openvswitch.org
> > http://openvswitch.org/mailman/listinfo/discuss
> >
>
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