Description of ML2 configuration options

Configuration option = Default value	Description
[ml2]
extension_drivers =	(ListOpt) An ordered list of extension driver entrypoints to be loaded from the neutron.ml2.extension_drivers namespace.
mechanism_drivers =	(ListOpt) An ordered list of networking mechanism driver entrypoints to be loaded from the neutron.ml2.mechanism_drivers namespace.
path_mtu = 0	(IntOpt) The maximum permissible size of an unfragmented packet travelling from and to addresses where encapsulated Neutron traffic is sent. If <= 0, the path MTU is indeterminate.
physical_network_mtus =	(ListOpt) A list of mappings of physical networks to MTU values. The format of the mapping is <physnet>:<mtu val>. This mapping allows specifying a physical network MTU value that differs from the default segment_mtu value.
segment_mtu = 0	(IntOpt) The maximum permissible size of an unfragmented packet travelling a L2 network segment. If <= 0, the segment MTU is indeterminate.
tenant_network_types = local	(ListOpt) Ordered list of network_types to allocate as tenant networks.
type_drivers = local, flat, vlan, gre, vxlan	(ListOpt) List of network type driver entrypoints to be loaded from the neutron.ml2.type_drivers namespace.