gtpg1m0j | General Information |
Figure 10 shows TPF communication support through multiple Systems Network Architecture (SNA) computer networks. The TPF system allows the sharing of lines, terminals, and applications in an integrated network of computing systems. An ACF/VTAM communications management configuration (CMC), which resides in a central processor complex (CPC) other than the TPF system, is necessary for all SNA communication. The CMC and its associated network management products provide services such as resource and configuration ownership and management, session establishment, problem determination, and operational management for the resources in the network.
Figure 10. TPF Communication Support
The TPF system supports the Airlines Line Control Interconnection (ALCI) feature of the Network Control Program (NCP) to extend SNA benefits to Airlines Line Control (ALC) communication networks. This extends SNA's inherent advantages of function, connectivity, and network management capability to ALC users. The TPF system's support of the ALCI feature of NCP permits ALC lines to interface to the SNA network, allowing greater use of SNA networking facilities and the potential for controlling line costs through consolidation. The TPF system can attach to an SNA network as either a type 2.1 node or a type 5 data host. The TPF system attaches to the SNA network by means of 3745 communication controllers running the currently supported level of the Network Control Program (NCP). The TPF system can take advantage of the network management capabilities of VTAM. The ACF/VTAM application facility, Logon Manager, provides support for establishing a TPF session as a type 2.1 node. As a type 5 data host, the TPF system must be in an adjacent SNA network, communicating through the services of SNA Network Interconnection (SNI) gateways provided by the channel-attached NCPs. The ability of the TPF system to support both connections to the network allows users to move the TPF system to a type 2.1 node without disrupting their existing network. The TPF system supports cross-system message routing. Data can be transmitted across TPF CPCs without communications management configuration (CMC) intervention after a session is established.
TPF sessions between two logical units are not interrupted by the restart of a failed CMC. Ownership changes resulting from the restart are reflected in the TPF system without a network generation.
The SNA Network Interconnection (SNI) facilities allow the TPF system to connect to a full function SNA network. SNI permits TPF type 5 data host users to take advantage of many advanced SNA networking facilities that are not supported by the TPF system as a data host. By separating TPF CPCs through an NCP gateway from the VTAM owner and network resources, facilities such as transmission groups, alternate paths, transmission priorities, and flow control can be used to improve the level of function and availability in the network.
Users of the TPF system as a type 2.1 node can take advantage of the same level of network function without SNI being required in the local NCPs.
The TPF system supports addressability via SNA Extended Network Addressing. This addressing provides selection of resources from a maximum of 255 NCPs, each having 64KB resources, to a maximum of 16-MB resources in the TPF network. Of importance to the system user is the ability to maintain NCP and VTAM currency and release consistency across the entire network.
The TPF system as a type 2.1 node supports the multiple channel attachment abilities of the 3745 communication controller. This allows one 3745 communication controller to be shared by several processors. A 3745 can support up to 16 host systems, and Enterprise Systems Connection (ESCON) supports up to 64 host systems.