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Terminate Offload Requested by an Offload Target

  • Articolo

[The TCP chimney offload feature is deprecated and should not be used.]

An offload target can request the host stack to terminate the offload of either a single TCP connection or all TCP connections.

Requesting the Termination of a Single TCP Connection

To request the termination of the offload of a single TCP connection, the offload target calls the NdisTcpOffloadEventHandler function with the EventType parameter set to TcpIndicateRetrieve. The offload target specifies the reason for the termination request as a TCP_UPLOAD_REASON value in the EventSpecificInformation parameter that it passes to the NdisTcpOffloadEventHandler function. In response, the host stack calls the offload target's MiniportTerminateOffload function as soon as possible.

The offload target can request the termination of only one TCP connection with each call to the NdisTcpOffloadEventHandler function. The offload target cannot request the termination of a neighbor state object or a path state object. For a description of events or circumstances that can cause an offload target to request the termination of the offload of a TCP connection, see the NdisTcpOffloadEventHandler function.There is no restriction on how many times an offload target can request the termination of the offload of a TCP connection.

Note that the host stack can terminate the offload of a TCP connection regardless of the state of that connection. In all such situations, the offload should comply with the termination request, if possible.

Requesting the Termination of All Offloaded TCP Connections

An offload target can request the termination of all TCP connections that have been offloaded to it. To request such a termination, an offload target calls the NdisMIndicateStatusEx function with the NDIS_STATUS_INDICATION-> StatusCode member set to NDIS_STATUS_UPLOAD_ALL. After completing the termination operation, the offload target can call the NdisMIndicateStatusEx function with the NDIS_STATUS_INDICATION-> StatusCode member set to NDIS_STATUS_OFFLOAD_RESUME. This value indicates to the host stack that the host stack can resume offloading TCP connections to the offload target.

This functionality might be used by an 802.3ad-capable intermediate driver when failing over from one network interface card (NIC) to another NIC.