[openstack-dev] [Kuryr] Overlay MTU setup in docker remote driver

Liping Mao (limao) limao at cisco.com
Wed Aug 17 00:55:27 UTC 2016

Hi Ihar,

Thanks for your comments.
Agree, kuryr need to load mtu in neutron network.

I submit a bug to track this:

And patch sets are here:

Generally, when kuryr create docker interface, it call
neturon network api to get mtu, then set it on the interface.


Liping Mao

On 16/8/17 上午8:20, "Ihar Hrachyshka" <ihrachys at redhat.com> wrote:

>Liping Mao (limao) <limao at cisco.com> wrote:
>> Hi Kuryr team,
>> When the network in neutron using overlay for vm,
>> it will use dhcp option to control the VM interface MTU,
>> but for docker, the ip address does not get from dhcp.
>> So it will not set up proper MTU in container.
>> Two work-around in my mind now:
>> 1. Set the default MTU in docker to 1450 or less.
>> 2. Manually configure MTU after container start up.
>> But both of these are not good, the idea way in my mind
>> is when libnetwork Call remote driver create network,
>> kuryr create neutron network, then return Proper MTU to libnetwork,
>> docker use this MTU for this network. But docker remote driver
>> does not support this.
>> Or maybe let user config MTU in remote driver,
>> a little similar with overlay driver:
>> https://github.com/docker/libnetwork/pull/1349
>Please don’t allow to configure MTU in any specific way, just make sure
>that the MTU value on neutron network is applied on the container side.
>Also, enforcing it to 1450 is not going to work for lots and lots of
>Enforcing it to anything won’t work, because MTUs depend on network type.
>> But now, seems like remote driver will not do similar things.
>> Any idea to solve this problem? Thanks.
>> Regards,
>> Liping Mao
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