Remote system session establishment is slightly different for a type 2.0 (T2.0) node than for a type 2.1 (T2.1) node. Session establishment for each node type is explained below, and examples of session establishment activities between the HP 3000 and the IBM remote system are shown later in this chapter.
For a Type 2.0 Node |
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The System Services Control Point (SSCP) uses PU-SSCP sessions to control the PU in each node in its domain. Each PU, in turn, controls the resources of the node it resides in. These resources include the links which have been configured for the particular node. The SSCP transmits an ACTivate Physical Unit (ACTPU)
command request to the PU to establish a session with the PU. When a PU-SSCP session is activated, the node that contains that PU becomes an active node in the SNA network. SNA Transport manages the PU-SSCP sessions of the HP 3000.
The SSCP uses LU-SSCP sessions to control dependent LUs and to establish dependent LU-LU sessions. The SSCP sends the command ACTivate Logical Unit (ACTLU)
to establish LU-SSCP sessions. SNA Transport manages LU-SSCP sessions on the HP 3000.
A dependent LU-LU session enables data to be exchanged between two end users, between an end user and an application running on the host processor (such as TSO), or between a job and the Job Entry Subsystem (for example, JES2) running on the host. The LU-LU session can be thought of as a temporary logical connection that allows two LUs to exchange data.
LUs on the HP 3000 communicate with the SSCP to establish
dependent LU-LU sessions. A dependent LU sends a session initiation request to the SSCP via its LU-SSCP session. The SNA services manage the LU-LU sessions on the
HP 3000.