The Network.Type enumerated type defines the type of a vCenter Server network. The type of a network can be used to determine what features it supports and which APIs can be used to find more information about the network or change its configuration.
STANDARD_PORTGROUP : XXX: ESX based (created and managed on ESX)
DISTRIBUTED_PORTGROUP : XXX: vCenter based (create and managed through vCenter)
OPAQUE_NETWORK : A network for whose configuration is managed outside of vSphere. The identifer and name of the network is made available through vSphere so that host and virtual machine virtual ethernet devices can connect to them.
Enumeration: DISTRIBUTED_PORTGROUP, OPAQUE_NETWORK, STANDARD_PORTGROUP,