gtps4m1fSystem Generation

High Performance Option Feature

Both the loosely coupled facility (LC) and the multiple database function (MDBF) of TPF/HPO present unique communications considerations for users of either or both options, LC or MDBF.

Loosely Coupled Communications Considerations

ACF support is a prerequisite for the use of LC because the individual processors of the LC complex are connected to one another by MSNF and the multitail channel connection feature of the 37x5 (in addition to the DASD connection provided by the ELLF RPQ on the DASD control units). This allows each processor in the LC complex direct access to all SDLC and NEF supported ALC devices. This use of MSNF and SNA networking is just an LC implementation technique that is allowed by the fact that TPF/ACF support already supports the connection of multiple TPF/ACF systems. The difference, is that the various TPF/ACF systems are also loosely coupled together via the ELLF RPQ. It should also be noted that an LC complex may also be connected via MSNF to other hosts and their communication networks, including other TPF/HPO LC complexes.

Normally, all but one of the LC processors can be active at one time with the other connected to the 37x5 acting as a backup processor in the event of a switchover from any of the other processors. Outside of any 37x5 hardware limitations, the HPO feature itself supports as many as 32 processors loosely coupled together.

The use of 3705 EP or 3745 PEP in an LC configuration presents a problem because support for a multitail connection to multiple hosts is not provided by the 3705 EP or the 3745 PEP. As a result, LC employs the concept of a single EP processor, which is located in the LC complex, to which is attached the TCUs running 3705 EP. This EP processor is also the only one that is allowed to have 3270 local control units and terminals attached to it except for native console support. This means that all applications or functions that are only associated with the non-SNA network must be associated with the EP processor. For example, support facilities such as message switching (MESW) (see Message Switching Packages) are also located in the EP processor.

System generation of communications support for LC is basically the same as generating a TPF system with ACF support with the exceptions noted later. Support for the LC facility itself is the result of the user installing the HPO feature and specifying multiple TPF processor IDs on the SYSID parameter of SIP's CONFIG macro. In addition to the generation procedures outlined later on in this section, users are also directed to several of the communications and system support packages that appear in Application and System Support, and especially Message Router Support.

Multiple Database Function Communications Considerations

In a TPF/HPO system with MDBF, communication support is a shared resource with all communications support functions being located in the basic subsystem (BSS). As a result, the communications database is only generated for the BSS and is not relevant to the other subsystems. An exception to this rule is the AAA/RCB initialization table (UAT), which is generated as part of the communication pilot record process (see Communication Pilot Record Generation).

Terminals, which are defined by the UAT, are supported by the BSS, but at any given time are connected or logged to an application that is located in a particular subsystem user or subsystem. (See Message Router Support and Log Processor.) As a result, there needs to be a UAT definition by subsystem for all terminals that can log to applications located in that subsystem. In theory, all subsystems could define all terminals, or a particular subsystem only has to define those terminals in its UAT that will log to it. The BSS itself needs a definition of all terminals on the system.

Note:
All non-SNA terminals are defined in the UAT. For SNA devices only, 3270/SDLC and all NEF terminals, which communicate with old applications, need an entry in the UAT. This entry is the pseudo address that will be associated with the terminal when it is logged to an old application.

Support for MDBF itself, including communications support, comes as a result of a user coding SIP SSDEF macro. In addition, unique MDBF parameters are associated with other communications macros that will be noted as they are discussed.