3.1. OSI Model

Communications between computers over networks are made possible by protocols. A protocol is a set of rules and restrictions that define how data is transmitted over a network medium (for example, twisted-pair cable, wireless transmission, and so on). In the early days of network development, many companies had their own proprietary protocols, which meant interaction between computers of different vendors was often difficult, if not impossible. In an effort to eliminate this problem, the International Organization for Standardization (ISO) developed the OSI Reference Model for protocols in the early 1980s. Specifically, ISO 7498 defines the OSI Reference Model (more commonly called the OSI model). Understanding the OSI model and ...

Get CISSP®: Certified Information Systems Security Professional: Study Guide, Fourth Edition now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.