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

[Shridhar Sahukar]

Hi Gurucharan,

The ping does work when both the hosts are in the same subnet. I guess
there is no ARP in that case right?

Regards,
Shridhar



On Tue, Jul 15, 2014 at 9:01 AM, Gurucharan Shetty <shettyg at nicira.com>
wrote:

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