19.1 Chapter Objectives

• Describe DECnet IV concepts

• Describe DECnet IV management

• LAT concepts

• Describe LAT management

19.2 Introduction

Before the early 1980s, most users interacted with Digital systems using directly connected terminals (figure 19.1). Frequently, systems operated in a stand-alone manner and were not connected to any type of network. To transfer data between systems you had to copy it to magnetic media and physically transport it to another system.

Figure 19.1: Directly Wired Terminals

As the installed base of systems and PCs swelled, transporting magnetic media from host to host ( sneaker-net ) became impractical direct file transfer between systems was desperately needed. Users also needed to access more than one host from a single terminal, and many hosts needed to access common printers. Digital developed the DECnet protocol (and its associated applications) to address the file-transfer requirement. Digital later developed the LAT protocol to provide greater flexibility and performance for terminal-based connectivity.

Today, OpenVMS systems can be networked by means of a wide variety of physical connections (e.g., Ethernet, FDDI, Token Ring, serial line). OpenVMS systems can communicate using many other protocols (e.g., TCP/IP, Novell IPX). However, because most Digital users rely on DECnet and LAT protocols on Ethernet, this chapter focuses on that environment.

DECnet-Plus (called DECnet V and DECnet/OSI in the early 1990s) is the preferred product today. This chapter discusses its predecessor, DECnet IV, in detail. The reader is cautioned that some key concepts have changed between the two products. In particular, DECnet IV is managed by NCP,...