[ovs-discuss] Geneve and IPv6

[Gregory Rose]

On 5/1/2018 6:53 PM, Ben Pfaff wrote:
> Hi Greg.
>
> We've had multiple reports now that Geneve kernel-based tunnels do not
> work in Open vSwitch if IPv6 is not enabled.  Do you have an idea
> whether we should consider this a bug in OVS or a bug in the
> documentation?  That is, should we plan to fix it (when we can) or
> should we plan to document that Geneve requires IPv6?  (Or is something
> else going on?)
>
> No rush.
>
> Thanks,
>
> Ben.

Sorry for the late response.  It is just how the Linux kernel is 
configured.  There was an internal bug
filed a few months ago where I found that geneve depends on a certain 
kernel configuration that
cannot be overridden and disabling ipv6 causes the check for the 
configuration to always fail.

The upshot is that there is no fix without making changes to the 
upstream Linux kernel.  It is a Linux
kernel limitation and should probably be documented as you say, i.e. 
"Geneve requires ipv6".

Thanks,

- Greg

>
> On Mon, Apr 30, 2018 at 10:25:06AM +0200, Matthias May wrote:
>> On 27/04/18 14:20, Paul Greenberg wrote:
>>> When IPv6 is disables in `/boot/grub2/grub.cfg`:
>>>
>>> ```
>>> linux16 ... ipv6.disable=1
>>> ```
>>>
>>> Then GENEVE interface does not come up properly.
>>>
>>> ```
>>> # ovs-vsctl show
>>>          Port "ovn-14a54f-0"
>>>              Interface "ovn-14a54f-0"
>>>                  type: geneve
>>>                  options: {csum="true", key=flow, remote_ip="10.10.10.10"}
>>>                  error: "could not add network device ovn-14a54f-0 to ofproto (Address family not supported by protocol)"
>>> ```
>>>
>>> Additionally, run the following commands:
>>>
>>> ```
>>> # cat /proc/version
>>> Linux version 3.10.0-514.21.1.el7.x86_64 (mockbuild at x86-020.build.eng.bos.redhat.com) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-11) (GCC) ) #1 SMP Sat Apr 22 02:41:35 EDT 2017
>>>
>>> # ovs-vswitchd --version
>>> ovs-vswitchd (Open vSwitch) 2.9.0
>>> ```
>>>
>>> When IPv6 is enabled, then OVN works properly.
>>> _______________________________________________
>>> discuss mailing list
>>> discuss at openvswitch.org
>>> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>>>
>> Hi
>> I remember running into the same when playing around with GRE on a system where IPv6 was disabled.
>>
>> BR
>> Matthias
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