gtpc3m29Concepts and Structures

Communication Interfaces

The TPF system supports a variety of network protocols with most being supported through the systems network architecture (SNA). These include SDLC, CTC, X.25, ALC, and Token Ring. The non-SNA protocols are BSC, SLC, and 3270 local.

The primary SNA interface is through channel-connected communication controllers running NCPs, although a CTC interface is also supported. The TPF system recognizes a wide variety of SNA LU types (LU0, LU1, LU2, LU3, LU 6.2) with a wide variety of terminal types (such as 3600/4700, 327x, 328x, PS/2, AS/400, RISC System/6000).

In a loosely coupled complex, emulator program (EP) protocols (that is BSC and SLC) must be connected to a single CPC, known as the EP processor.

As a participant in a full function network, the TPF system supports two different interfaces to the SNA network:

The function of the TPF system within an SNA network is to act as a data host where network information and management are assumed to be handled by a VTAM communications management configuration (CMC). The TPF system manages the applications within its complex, the channel interfaces to locally attached communication controllers, and the range of terminals and LU types connected to the TPF system.

Error Recovery

In keeping with the TPF philosophy to recover quickly when a system error occurs, there are several design points in communications control for this purpose:

Function Management Message Router (FMMR)

Functional management message router (FMMR) is a TPF routing mechanism that permits an application in a TPF system to send a message (data) to an application in another TPF system. That is, the destination TPF system is remote and out of complex to the origin TPF system. Therefore, if the origin TPF system is a uniprocessor, all other CPCs running the TPF system are remote. If the origin TPF system is loosely coupled, then the destination TPF system is a CPC that is external to the origin loosely coupled complex.

Only the SNA link protocol is supported for sending a message to a remote TPF application.

Interprocessor Communications (IPC)

Interprocessor communication is the mechanism that is used for communication between the CPCs in a loosely coupled (LC) complex; that is, remote and in complex.

Conceptually, IPC can be viewed as a communication facility that is internal to the TPF system and uses the MPIF channel-to-channel protocol.

User Exits

The TPF system provides a variety of user exits to allow a user installation to tailor system processing to address unique requirements. There are user exits within communications control, such as message recovery, transaction routing for input messages, ROUTC for output messages, COMM SOURCE, and processing selection vectors, which are activated based on the LU name of the input source.