HP-UX SNAplus2 General Information (October 1998)

14 Chapter 1

SNA Networking

Overview

SNAplus2 provides Systems Network Architecture (SNA) networking

support for HP-UX systems. SNA is a set of protocols devised by IBM to

facilitate communications between computers.

Over the years, SNA has evolved considerably. Initially, SNA was heavily

oriented towards accessing host computers, and relied on the host to

control the entire network. Each network or sub-network was controlled

by the host; other computers communicated directly with the host but

not with each other. This old-style SNA is called “subarea SNA,” and is

still widely used.

Today, SNA provides powerful and ﬂexible networking capabilities,

enabling direct peer-to-peer communications between computers in the

network (without requiring the intervention of the host). In a full-ﬂedged

peer-level network, elements in the network can communicate as

required; but no single computer is in control of the network. This

new-style SNA is called “APPN” (Advanced Peer-to-Peer Networking).

Many SNA networks have elements of both subarea and peer-to-peer

networking. As networks migrate from subarea SNA to APPN, an

APPN-capable host can control older systems while acting as a peer to

newer systems. Similarly, a single computer can access both peer

computers (in an APPN network) and a host computer (in a subarea

network). Communication with the host is controlled by the host;

communication with other computers is peer-to-peer and does not

involve the host.