[ovs-discuss] Help with GRE Tunnels

[Justin Brown]

Hi Jesse,

Thanks for the response. I finally got a chance to take a deeper look.

Fedora bundles a useless openvswitch module with it's default kernel.
One of the machines was using this faulty module, and I only realized
it once I started paying attention to the module size from lsmod.

Cheers,
Justin

On Tue, Aug 6, 2013 at 4:20 PM, Jesse Gross <jesse at nicira.com> wrote:
> On Mon, Aug 5, 2013 at 10:19 AM, Justin Brown <justin.brown at fandingo.org> wrote:
>> Hello,
>>
>> With Pravin's help over on the dev list, I got Openvswitch running on
>> Linux 3.10 over the weekend with the proper kernel module. I'm trying
>> to use Openvswitch with Openstack Quantum, but I'm having some trouble
>> with Openvswitch. Openstack seems to set everything up properly, so I
>> just need some help looking into what's happening in the Openvswitch
>> black box.
>>
>> Here's the simple setup that I'm trying to get working before
>> expanding. There is a Quantum server that has a static IP of
>> 192.168.26.10/24. There is a compute node that has a static IP of
>> 192.168.26.20/24. The communication between these nodes works fine.
>>
>> Openstack has setup a private network at 10.0.1.0/24 and is supposed
>> to have a DHCP server listening on a tap device tap4f517c5d-c3 at
>> 10.0.1.3. Note that the ovs port for this tap device is automatically
>> created by Openstack, but the Linux interface is not. For
>> troubleshooting, I did `tunctl -t tap4f517c5d-c3 && ip add add
>> 10.0.1.3/24 && ip link set up tap4f517c5d-c3`.
>>
>> I deployed VM A to the compute node that has IP 10.0.1.2/24. VM A
>> could not receive a DHCP address, so I manually assigned one. I
>> deployed a second VM, VM B, to the same compute node and manually
>> assigned IP 10.0.1.4/24.
>>
>> VMs A and B can communicate fine, so the internal bridge br-int is
>> working. However, I cannot communicate with the tap device on the
>> other server. It seems like br-tun is broken or the patch interface
>> between br-tun and br-int is not working.
>>
>> Bascially, from what I can tell, Openstack Quantum is working fine and
>> without error, and Openvswitch is not throwing any errors, but the GRE
>> tunnel doesn't seem to be working. I've tried looking at a variety of
>> tcpdumps on 'net 10.0.1.0/24' on several different interfaces, but I
>> can't get a handle on how Openvwitch is processing traffic.
>
> What does tcpdump show on the physical interface? Are you sure that
> GRE isn't filtered on your underlying network?