CHAPTER 9:COMMUNICATIONS & NETWORKS

Connectivity

Connectivity is the unbiased transport of packets between two end points. This is also the essential definition of "IP" (Internet Protocol). There is a strong boundary between the IP layer and the applications built upon it. TCP, for example, is an application protocol. In the term "TCP/IP" the slash emphasizes the separation of the two.

Communication systems

E-mail

Instant Messaging

Internet telephone

Electronic commerce

Wireless revolution

Means in simple terms the replacement of wires used for communication , by wireless environment.For instance Local area network (LAN) has been replaced by WLAN ( Wireless LAN ) , similarly fixed line telephones have been replaced by Mobile hand sets including satellite handsets.

Networks

A network is a group of two or more computer systems linked together. There are many types of computer networks, including:

local-area networks (LANs) : The computers are geographically close together (that is, in the same building).

wide-area networks (WANs) : The computers are farther apart and are connected by telephone lines or radio waves.

campus-area networks (CANs): The computers are within a limited geographic area, such as a campus or military base.

metropolitan-area networks MANs): A data network designed for a town or city.

home-area networks (HANs): A network contained within a user's home that connects a person's digital devices