Open Stack

Clark Boylan <cboylan at sapwetik.org> wrote:

> On Mon, Jan 11, 2016, at 12:35 PM, Sean M. Collins wrote:
>> Nice find. I actually pushed a patch recently that we should be
>> advertising the MTU by default. I think this really shows that it should
>> be enabled by default.
>>
>> https://review.openstack.org/263486l
> ++ Neutron should be able to determine what the outer MTU is and adjust
> the advertised inner MTU automatically based on the overhead required
> for whatever tunnel protocol is in use all without the deployer or cloud
> user needing to know anything special.

Let me clarify: there is still requirement for the image you boot to honour  
one of the ways we advertise MTU from neutron (DHCP MTU opton; RA for IPv6  
networks; …) Neutron cannot change mtu for the device that is seen from  
inside of the instance.

That said, most real images, including cirros since last year, should  
support the DHCP option.

Ihar