3.3.5.3.4 Processing an Internal IO Control Message
The structure and fields of the INTERNAL_IO_CONTROL message are specified in section 2.2.6.4.
After receiving the INTERNAL_IO_CONTROL message, the client MUST forward the request to the physical device by using the same rules as specified in section 3.3.5.3.3. When the physical device completes the request, the client MUST send the result of the request to the server via the IOCONTROL_COMPLETION message and the RequestId field in the IOCONTROL_COMPLETION message MUST match the RequestId in the INTERNAL_IO_CONTROL message.
The INTERNAL_IO_CONTROL message contains OutputBufferSize field. This indicates the maximum amount of data the client can send to the server when sending the final result of this request. If the physical device returns more data than the OutputBufferSize field specifies, the client MUST terminate the dynamic virtual channel.