Comment 1 for bug 1741954

As Armando pointed out, even in 'good' runs those scenarios take a lot of time, so we probably just hit the edge of the timeout allowed by neutronclient. We may optimize db operations when validating trunk requests, specifically, we could fetch all networks at once to validate MTU compatibility, offloading bulking to db native layer.

We have a similar code that bulk-fetches networks here: https://github.com/openstack/neutron/blob/master/neutron/services/trunk/rules.py#L191 that we may somewhat reuse.