gtpc3m25 | Concepts and Structures |
In the early versions of the TPF system, the technology of communication systems forced the TPF system to provide many of the functions that were later provided by a network control program (NCP) running in a communication controller. Subsequently, Internet technology is replacing these older technologies that are often proprietary and require specialized hardware. Internet technology accommodates multiple, diverse underlying hardware technologies by adding both physical connections and a set of conventions. Because of the longevity of the TPF system, it continues to support the older technologies and takes advantage of newer ones.
Non-SNA communications control remains in the TPF system to preserve long-established interfaces and is discussed only minimally; there is an emphasis on SNA communications and Transmission Control Protocol/Internet Protocol (TCP/IP) support.
Non-SNA and SNA Communications: The terminology non-SNA and SNA within the TPF vernacular is rather artificial, being primarily based on whether a message using a particular communications protocol arrives at a central processing complex (CPC) through a communication controller:
Messages arriving through an EP controller and 3270 local controller are handled by non-SNA communications control. SNA communications handles the rest. Figure 57 shows these various options.
Communications control is a collection of programs that support the various communication protocols that are recognized by the TPF system. Components of communications control manage the communications resources for a TPF computing facility and are an integral part of the TPF control program. This is a fundamental, performance-related difference between the teleprocessing support performed by the TPF system and other teleprocessing access methods (such as Virtual Telecommunications Access Method (VTAM)), used by transaction processing subsystems (such as Information Management System (IMS)), found in a general purpose operating system (such as MVS).
TCP/IP Communications: TCP/IP supports an interconnection of computer networks that provides universal communication services; a computer network is a group of connected nodes used for data communication. A computer network configuration consists of data processing devices, software, and transmission media linked for information exchange.