Multicast object identifier (OID) requests, including OID_802_3_ADD_MULTICAST_ADDRESS and OID_802_3_DELETE_MULTICAST_ADDRESS, are issued by overlying protocol and filter drivers that run in the following:
The management operating system that runs in the Hyper-V parent partition.
The guest operating system that runs Windows Vista or a later version of the Windows operating system in the Hyper-V child partition.
The extensible switch interface forwards these OID requests down the extensible switch control path. This allows the extensions to obtain configuration information about the network interface that is used in the partition.
For example, the protocol edge of the extensible switch forwards an OID set request of OID_802_3_ADD_MULTICAST_ADDRESS from a child partition down the extensible switch control path. This allows extensions to obtain the multicast address configuration that is used by the networking interface in that partition.
When these multicast OID requests arrive at the extensible switch interface, the protocol edge of the extensible switch encapsulates the OID request within an NDIS_SWITCH_NIC_OID_REQUEST structure. The protocol edge also sets the members of this structure in the following way:
The SourcePortId and SourceNicIndex members are set to the corresponding values for the port and network adapter used by the partition from which the OID request originated.
Note If the multicast OID request was originated from the management operating system, the protocol edge sets these members to the values for the extensible switch internal network adapter.
The DestinationPortId and DestinationNicIndex members are set to zero. This specifies that the encapsulated OID request is to be delivered to extensions in the control path.
The OidRequest member is set to the address of an NDIS_OID_REQUEST structure for the encapsulated OID request.
The protocol edge then issues the OID_SWITCH_NIC_REQUEST request to forward the encapsulated OID request down the extensible switch control path. Underlying forwarding extensions can inspect these encapsulated OID requests and retain the multicast address information that they specify. For example, the extension may need this information if it originates multicast packets that it forwards to an extensible switch port.
For more information about the extensible switch control path, see Hyper-V Extensible Switch Control Path.