Default or not, depends on how you see it. 1500 is the most common MTU, so that setting is 1500 by default. Makes perfect sense to me.

Thanks!
Tony 

On Sep 23, 2024 2:07 PM, Łukasz Chrustek <lukasz@chrustek.net> wrote:

Hi Tony,

yes, I'm aware that, and already found it, thanks anyway :), but - is there any reason why this settings isn't default ?

> With this setting in neutron.conf, instance will get MTU 1500.

> [DEFAULT]
> global_physnet_mtu = 1558


> Thanks!
> Tony
> ________________________________________
> From: Łukasz Chrustek <lukasz@chrustek.net>
> Sent: September 23, 2024 11:22 AM
> To: openstack-discuss
> Subject: Network MTU setting in ovn/ovs

> Hi,

> I have a question about increasing MTU for tenant network. Now it set to 1442 by default on geneve baked tenant network.
> Is there any drawbacks or it is some kind of bad practice to increase this MTU to 1500 bytes or higher ?

> We had an issue with one migrated instance from older version of openstack (where was linuxbrigde configured), there mtu was set to 1500, so the settings for i.e. docker inside the vm was set respectively to the higher value.

> --
> Best regards
>  Lukasz Chrustek




--
Regards
Lukasz Chrustek