2.2.15.2 Client Initiate Multitransport Response PDU

The Initiate Multitransport Response PDU is sent by the client to the server and is used to indicate to the server whether the client was able to complete the multitransport initiation request associated with the ID specified in the requestId field.

This PDU MUST only be sent over the MCS message channel. The ID of the message channel is specified in the Server Message Channel Data (section 2.2.1.4.5).


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tpktHeader

x224Data

mcsSDrq (variable)

...

securityHeader (variable)

...

requestId

hrResponse

tpktHeader (4 bytes): A TPKT Header, as specified in [T123] section 8.

x224Data (3 bytes): An X.224 Class 0 Data TPDU, as specified in [X224] section 13.7.

mcsSDrq (variable): A variable-length PER-encoded MCS Domain PDU (DomainMCSPDU) that encapsulates an MCS Send Data Request structure (SDrq, choice 25 from DomainMCSPDU), as specified in [T125] section 11.32 (the ASN.1 structure definitions are given in [T125] section 7, parts 7 and 10). The userData field of the MCS Send Data Request contains a Security Header and a Control PDU Data structure (section 2.2.1.15.1).

securityHeader (variable): Security header. The format of the security header depends on the Encryption Level and Encryption Method selected by the server (sections 5.3.2 and 2.2.1.4.3). This field MUST contain one of the following headers:

  • Basic Security Header (section 2.2.8.1.1.2.1) if the Encryption Level selected by the server is ENCRYPTION_LEVEL_NONE (0).

  • Non-FIPS Security Header (section 2.2.8.1.1.2.2) if the Encryption Method selected by the server is ENCRYPTION_METHOD_40BIT (0x00000001), ENCRYPTION_METHOD_56BIT (0x00000008), or ENCRYPTION_METHOD_128BIT (0x00000002).

  • FIPS Security Header (section 2.2.8.1.1.2.3) if the Encryption Method selected by the server is ENCRYPTION_METHOD_FIPS (0x00000010).

The flags field of the security header MUST contain the SEC_TRANSPORT_RSP (0x0004) flag (section 2.2.8.1.1.2.1).

requestId (4 bytes): A 32-bit unsigned integer that MUST contain the ID that was sent to the client in the requestId field of the associated Initiate Multitransport Request PDU (section 2.2.15.1).

hrResponse (4 bytes): A 32-bit unsigned integer that specifies a response code.

Value

Meaning

E_ABORT

0x80004004

Indicates that the client was unable to successfully establish the multitransport connection.

S_OK

0x00000000

Indicates that the client was able to successfully complete the multitransport initiation request.

This response code MUST only be sent to a server that advertises the SOFTSYNC_TCP_TO_UDP (0x200) flag in the Server Multitransport Channel Data (section 2.2.1.4.6).