Hitachi US7070447-001 manual Chapter Fundamentals of Networking, Doc Part Number, Version Number

Chapter 5

Fundamentals of Networking

Today, there are many different types of computers and networking equipment available. These devices are expected to communicate with each other. For this reason, it is extremely important that a set of rules be established and implemented in order for networking devices to function well together.

In 1978, the International Standards Organization (ISO) defined the Open System Interconnection (OSI) Model for networking. This reference model outlines the communications protocols used when transporting data from one network node to another. The standard was initially written to provide both hardware and software vendors a common platform on which to develop products. The model also serves as the basis for the IEEE LAN standards.

The OSI Model divides the task of computer communications into seven layers. The model represents a hierarchical structure and is designed so that each layer performs a specific service transparently to layer above and below it. In addition, the corresponding layers between two adjacent devices communicate to each other in a peer to peer relationship.

The Figure 5-1 shows the seven layers in the OSI Model in a peer-to-peer relationship

Doc Part Number, Version Number 5-1