PLU Session Characteristics

The local node provides support on the PLU session for FM profiles 2, 3, 4, and 7 and TS profiles 2, 3, 4, and 7. Support of these profiles means that the local node supports LU-LU session types 0, 1, 2, and 3. Using the PLU connection, the application can send and receive any FM data that is valid for the LU-LU types above.

The protocols appropriate to a particular session are determined by the parameters in the BIND request that establishes the session. The BIND parameters are reported to the application in the BICB on the Open(PLU) (OK) Confirm message. It is the application's responsibility to conform to the session protocols reported in the BICB.

Due to the wide range of BIND parameters allowable on a session and the options available to an application in the CICB on the Open(PLU) (OK) Response, this document does not attempt a complete description of the protocols for a particular session. The remaining topics in this section describe the general protocol characteristics of the PLU session, such as chaining, brackets, and so on.

Most of the protocol descriptions in the remainder of this section are accompanied by figures to illustrate the important features. The figures show:

• The relevant RH flags in SNA requests/responses.
• The sequence number of SNA requests/responses.
• Any sense data (shown as "SENSE=...") on SNA responses or Data messages.
• The ACKRQD field in Data and Status-Control messages.
• The relevant application flags (see Application Flags) in Data and Status-Control messages.
• The message key field in Data messages.
• Any error codes (shown as "ERROR=...") in Status-Acknowledge or Status-Control messages.

For simplicity, it is assumed that all messages are function management data flowing on the same PLU session that:

• Uses half-duplex flip-flop protocols.
• Uses brackets, with reset state of between-bracket.
• Does not use the PLU CICB segment delivery option (see Segment Delivery).