Understanding Networks and Network Security

Abstract

188 Let's say that the sender understands a different language and the receiver understands a different language. For discussion's sake, let's say the sender understands French and the receiver understands German. Assume that both have to exchange information, the media is Facsimile (FAX) in France and Telegraph in Germany. This communication has increased the complexity as both sender and receiver do not have a common language and there is no common media. The communication needs translators who understand both the languages or two translators-one who understands the sender's language (e.g., French) and another common language (e.g., English), another who understands a common language (e.g., English) and the receiver's language (e.g., German). These translators translate to the senders and receivers. A media translator transfers facsimile information on to the telegraphic information and vice versa. As shown in the Figure 9-2, this type of communication is called layered communication. Through the different layer, communication is achieved, each layer has a specific task, and tasks are broken down into simple and specific tasks. Though both sender and receiver do not have a common language, they are still able to interoperate with the help of layered communication. In the case of data communication, computer devices are connected logically to each other and data is transmitted from one computer system to another or from one device to another device as shown in Figure 9-3. A network connects two or more computers to communicate with each other or for the exchange of information among the systems. Networking is sharing of resources within the network. Data communication and computer networking go hand in hand. Data communication is the exchange of information across a medium and networking is connecting two devices to facilitate the exchange of information from one system to another in a connected network. When computer devices are connected in a network for communication, it consists of the following components: Message, Host, Receiver, Medium, and Protocol. When these network components (the host, receiver, medium, protocol, and other devices) are connected with each other, physically or logically, the primary consideration is whether the systems are able to communicate effectively with each other. Use of appropriate systems or network components with deployment of appropriate protocols ensures effective communication among the systems.