Network_Type
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 : vSphere standard portgroup (created and managed on ESX)
DISTRIBUTED_PORTGROUP : Distributed virtual portgroup (created and managed through vCenter)
OPAQUE_NETWORK : A network 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.