--- features: - By default, the DHCP agent provides a network MTU value to instances using the corresponding DHCP option if core plugin calculates the value. For ML2 plugin, calculation mechanism is enabled by setting [ml2] path_mtu option to a value greater than zero. upgrade: - To disable, use [DEFAULT] advertise_mtu = False. other: - For overlay networks managed by ML2 core plugin, the calculation algorithm subtracts the overlay protocol overhead from the value of [ml2] path_mtu. The DHCP agent provides the resulting (smaller) MTU to instances using overlay networks. - The [DEFAULT] advertise_mtu option must contain a consistent value on all hosts running the DHCP agent. - Typical networks can use [ml2] path_mtu = 1500.