gtps2m09ACF/SNA Data Communications Reference

TPF SNA Overview

The SNA support provided allows TPF to communicate with other systems including other TPF systems, or devices (both SNA and non-SNA, such as ALC) across an SNA interface.

Networks generally have a mix of systems, usually ACF/VTAMs and TPF.

It is required that an ACF/VTAM system, not TPF, be designated as the network manager (that is, the owner of the communications networks' resources), even if all or most of the data traffic is directed toward TPF.

Connections to the network can be both PU 5 connections and PU 2.1 connections. TPF as a PU 5 node connects to a communication controller running NCP or to an SNA channel-to-channel (CTC) device.

The TPF system can connect to a PU 2.1 network as either a low-entry networking (LEN) node or Advanced Peer-to-Peer Networking (APPN) node. In an APPN environment, the TPF system can only be an end node (EN), not a network node (NN).

TPF Network Control Program (NCP) support depends on:

All subsequent occurrences of NCP in the text of this book are superseded by the previous information, unless otherwise specified.

The SNA Network Interconnection (SNI) feature is required in the NCP to connect TPF as a PU 5 node. Format ID 4 (FID4) path information units (PIUs) are used to send messages across the connection. TPF's connection uses a single virtual route on the TPF side of the gateway, but sessions on the VTAMs side can take advantage of the full SNA functions available.

For SNA channel-to-channel (CTC), TPF appears to a remote host as a PU 5 (T5) node using FID4 PIUs. TPF and the remote system exchange identifications (XIDs) and are able to establish sessions across a maximum of 2 virtual routes using the CTC connection. Throughout the remainder of this publication, CTC will be used as an abbreviation for any SNA channel-to-channel link, device, and others.

TPF as a PU 2.1 node connects to NCP using the FID2 interface. As a PU 2.1 node, TPF no longer has a unique subarea but appears to the network as a PU in the subarea of each channel, attached NCP.

The TPF system also connects to a 3174 Advanced Peer-to-Peer Networking (APPN) controller as a PU 2.1 node. Sessions can be established between TPF applications and as many as 255 terminals (LUs) on a token ring connected to and managed by the 3174 controller. When the TPF system connects as a LEN node, only sessions using the LU 6.2 protocol are supported, and the sessions must be started by the remote LUs. When the TPF system connects as an APPN node and the 3174 is defined as an APPN network node, all LU protocols are supported.

The TPF system also connects to a RISC System/6000 system as a PU 2.1 node. When the TPF system connects as a LEN node, only sessions using the LU 6.2 protocol are supported, and the sessions must be started by the remote LUs. When the TPF system connects as an APPN node and the RISC System/6000 system is defined as an APPN network node, all LU protocols are supported.

For an Airlines Line Control (ALC) network, you must install the:

Note:
NEF/ALCI and NPSI are separate product, each with their own set of publications. This publication addresses only the support provided by TPF. Before generating the TPF system, read the publications of the other products to define the new network. See NPSI Planning and Installation and NPSI Host Programming for information on NPSI and GATE/FTPI.

Both TPF SNA and ALC support are required for TPF NEF, AX.25, and XALCI. SNA LUs can access new applications1. For 3270 SNA terminals, a pseudo address (LEID) can be defined to enable these terminals to access old applications. ALC terminals, using TPF-provided NEF/AX.25/XALCI support, can be used with old or new applications.

TPF can also interface with LUs using the LU 6.2 protocol. These LUs can access only applications that have been defined as LU 6.2 capable.

Note:
TPF's LU 6.2 support is provided through the TPF Advanced Program-to-Program Communications (TPF/APPC) support package. Refer to TPF Advanced Program-to-Program Communications for details about this support.

TPF supports the X.25 interface through the support of NCP Packet Switching Interface (NPSI). TPF provides connectivity support for the following Logical Link Control (LLC) types:

The High Performance Option (HPO) feature requires the TPF SNA support. HPO contains 2 components: the multiple database function (MDBF) and the loosely coupled facility (LC). These may be used separately or in combination.

When generating either of these components, the options needed for the system must be chosen ahead of time. In either case, the generation procedure involves the use of new macros plus new keywords on base generation macros. MDBF systems require a generation of each subsystem in addition to generating the base system. For LC systems only one base generation is performed, regardless of the number of processors in the complex.


Footnotes:

1
Old applications require a LNIATA (LEID) interface, while new applications can use either RIDs (Resource Identifiers) or LNIATAs (LEIDs).