---
features:
  - |
    The new ``net-mtu-writable`` extension API definition has been added. The
    new extension indicates that the network ``mtu`` attribute is writeable.
    Plugins supporting the new extension are expected to also support
    ``net-mtu``. The first plugin that gets support for the new extension is
    ``ml2``.
other:
  - |
    Changing MTU configuration options (``global_physnet_mtu``,
    ``physical_network_mtus``, and ``path_mtu``) and restarting
    ``neutron-server`` no longer affects existing networks' MTUs. Nevertheless,
    new networks will use new option values for MTU calculation. To reflect
    configuration changes for existing networks, one may use the new
    ``net-mtu-writable`` API extension to update ``mtu`` attribute for those
    networks.
