3.3.5.3.7 Sending MCS Attach User Confirm PDU

The structure and fields of the MCS Attach User Confirm PDU are described in section 2.2.1.7.

The tpktHeader field is initialized as described in [T123] section 8, while the x224Data field (which contains an X.224 Class 0 Data TPDU) is initialized as specified in [X224] section 13.7.

The MCS Connect Response PDU (embedded within the mcsCrsp field (section 2.2.1.4)) is described in [T125] section 7, parts 5 and 10.

If processing of the MCS Attach User Request was successful (section 3.3.5.3.6), the result field MUST be set to rt-successful (0), and the optional initiator field MUST be present and MUST contain an integer identifier that will be used to identify the user channel (this identifier MUST be stored in the User Channel ID store (section 3.3.1.2)). If processing of the MCS Attach User Request was not successful, then the optional initiator field SHOULD NOT be present and the result field MUST be set to rt-unspecified-failure (14).

If Enhanced RDP Security (section 5.4) is in effect, the External Security Protocol (section 5.4.5) MUST be used to encrypt the entire PDU and generate a verification digest before the PDU is transmitted over the wire.