Data Communications and Networking

Media Access Control (Data Communications and Networking)

Media access control refers to the need to control when computers transmit. With point-to-point full-duplex configurations, media access control is unnecessary because there are only two computers on the circuit and full duplex permits either computer to transmit at any time. Media access control becomes important when several computers share the same communication circuit, such […]

Error Control (Data Communications and Networking)

Before learning the control mechanisms that can be implemented to protect a network from errors, you should realize that there are human errors and network errors. Human errors, such as a mistake in typing a number, usually are controlled through the application program. Network errors, such as those that occur during transmission, are controlled by […]

Data Link Protocols (Data Communications and Networking)

In this section, we outline several commonly used data link layer protocols, which are summarized in Figure 4.7. Here we focus on message delineation, which indicates where a message starts and stops, and the various parts or fields within the message. For example, you must clearly indicate which part of a message or packet of […]

Transmission Efficiency (Data Communications and Networking)

One objective of a data communication network is to move the highest possible volume of accurate information through the network. The higher the volume, the greater the resulting network’s efficiency and the lower the cost. Network efficiency is affected by characteristics of the circuits such as error rates and maximum transmission speed, as well as […]

Implications For Management (Data Communications and Networking)

You can think of the data link layer protocol as the fundamental "language" spoken by networks. This protocol must be compatible with the physical cables that are used, but in many cases the physical cables can support a variety of different protocols. Each device on the network speaks a particular data link layer protocol. In […]

Network and Transport Layers (Data Communications and Networking)

The Network layer and transport layer are responsible for moving messages from end to end in a network. They are so closely tied together that they are usually discussed together. The transport layer (layer 4) performs three functions: linking the application layer to the network, segmenting (breaking long messages into smaller packets for transmission), and […]

Transport and Network Layer Protocols (Data Communications and Networking)

There are many different transport/network layer protocols, but one family of protocols, TCP/IP, dominates. Each transport and network layer protocol performs essentially the same functions, but each is incompatible with the others unless there is a special device to translate between them. Many vendors provide software with multiprotocol stacks, which means that the software supports […]

Transport Layer Functions (Data Communications and Networking)

The transport layer links the application software in the application layer with the network and is responsible for segmenting large messages into smaller ones for transmission and for managing the session (the end-to-end delivery of the message). One of the first issues facing the application layer is to find the numeric network address of the […]

Addressing (Data Communications and Networking)

Before you can send a message, you must know the destination address. It is extremely important to understand that each computer has several addresses, each used by a different layer. One address is used by the data link layer, another by the network layer, and still another by the application layer. When users work with […]

Routing (Data Communications and Networking)

In many networks, there are various possible routes a message can take to get from one computer to another. For example, in Figure 5.9, a message sent from computer A to computer F could travel first to computer B then to computer C to get to computer F, or it could go to computer D […]

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