Networking on z/OS
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APPN node types

Networking on z/OS

The building block for an APPN node is the T2.1 (low-entry networking, LEN) node. Be aware that T2.1 by itself does not provide any APPN functionality; additional software is required to make a T2.1 node an APPN node.

Depending on the software that implements APPN in T2.1 nodes, the node can be configured in the APPN networks with varying complexity, from the simplest case of an isolated pair of low-entry networking nodes to a large APPN network. Using low-entry networking or APPN protocols, any node can control the establishment and termination of sessions.

The following node types can be implemented by T2.1 nodes:
  • Low-entry networking (LEN)
  • APPN end node EN)
  • APPN network node (NN)
To ease the migration from subarea networking to APPN in the mainframe, the following nodes types can be implemented in a mainframe:
  • Interchange node (ICN)
  • Migration node

T5 and T4 nodes also support low-entry networking and APPN protocols, and are fully compatible with T2.1 nodes in these contexts. They also introduce product features of their own, related to enhanced subarea-APPN interchanges. When a subarea node implements either APPN or low-entry networking protocols, it acts as a T2.1 node and can still implement, depending on VTAM's definitions, the subarea T5 and T4 functions.

  • Low-entry networking (LEN) nodes
    Low-entry networking nodes, also referred to as T2.1 nodes, were introduced in the mid-1980s to address the requirement for peer networking. The low-entry networking node was the first stage of the APPN evolution.
  • End nodes (EN)
    APPN end nodes implement a subset of the full APPN functions and rely on one of the network nodes they are attached to for accessing the network, locating resources, and providing routing services.
  • Network nodes (NN)
    An APPN network node implements full APPN functionality and services. A collection of connected network nodes comprises the APPN backbone.
  • Specialized network node types
    APPN was designed for implementation on a wide range of hardware platforms and operating systems, including programmable workstations, desktop computers, UNIX and Windows servers, and the IBM mainframe. The APPN function and services for the various platforms are different, depending on the APPN node role. Therefore, APPN architecture defines basic and optional sets.
  • Specialized VTAM Nodes
Parent topic: SNA Advanced Peer-to-Peer Networking (APPN)

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