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Basics Of Data Communication: Part 7

This article will explain, Introduction to LAN, MAN and MAC, IEEE Standards, LAN, Topologies in very detailed.



Introduction to LAN, MAN and MAC

There are two types of Network Technology: Switch Networks and Broadcast Networks. In switch network, systems are interconnected by means of point-to-point transmission lines, multiplexers and switches. In switching Networks, the transfer of packet across networks requires routing, to direct packets from source to destination, as the source and destination stations will not be connected by a single transmission link most of the cases. But in Broadcast Networks, all the system are connected to common transmission medium, which acts as a broadcast medium making routing unnecessary. Since the transmission medium is shared by all the connected systems, there is a need for additional layer, consisting of Medium Access Control (MAC) Protocol to orchestrate the transmission from various systems. The role of MAC protocol is to co-ordinate the access to…

Basics of Data Communication: Part 8

This article will explain, MAN, MAC, MAC Frame Format, LLC, LAN Systems, CSMA and CD, CSMA and CD Frame Format, Token Right, FDDI, Bridge etc.



MAN (Metropolitan Area Network)

MAN is a computer network usually spanning a campus or a city, which typically connect a few local area networks using high speed backbone technologies. A MAN often provides efficient connections to a wide area network (WAN). There are three important features which discriminate MANs from LANs or WANs:
The network size falls intermediate between LANs and WANs. A MAN typically covers an area of between 5 and 50 km range. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings.
A MAN (like a WAN) is not generally owned by a single organization. The MAN, its communications links and equipment are generally owned by either a consortium of users or by a network service provider who sells the service to the users.
A MAN often acts as a high speed network to allow shar…

Basics Of Data Communication Part: 1

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This article will explain, Data Communication Model, Data Communication System Tasks and Communication Network and Services.


Introduction and Basics of Data Communication Model

Data Communications is the transfer of data or information between a source and a receiver. The source transmits the data and the receiver receives it. Data communication involved the following like communication networks, different communication services required, the kind of networks available, protocol architectures, OSI models, TCP/IP protocol models etc. Data Communication is interested in the transfer of data, the method of transfer and the preservation of the data during the transfer process.

In Local Area Networks, we are interested in "connectivity", connecting computers together to share resources. Even though the computers can have different disk operating systems, languages, cabling and locations, they still can communicate to one another and share resources.

The purpose of Data Communication…

Basics Of Data Communication: Part 6

This article will explain, High-level Data Link Control (HDLC), HDLC Frame Structure, HDLC Operation etc.



High-level Data Link Control (HDLC)

It is the most important data link control protocol is HDLC. It is not only widely used, but also it is the basis for many other important data link control protocols, which use the same or similar formats and the same mechanisms as employed in HDLC.

Characteristics of HDLC

To satisfy a variety of applications, HDLC defines three types of stations, two link configurations and three data-transfer modes of operation.

The three station types are:
Primary Station

It has responsibility for controlling the operation of the link. Frames issued by the primary are called commands.
Secondary Station

It has responsibility for controlling operations under the control of the primary station. Frames issued by a secondary are called responses. The primary maintains a separate logical link with each secondary station on the line.
Combined Station

It combines the features…

Basics of Data Communication: Part 4

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This article will explain about, Transmission Media, Guided Transmission Media, Twisted Pair, Coaxial Cable, Optical fiber, Wireless Transmission media, Multiplexing, Circuit Switching etc.



Transmission Media

In data transmission system, transmission medium is used between transmitter and receiver. Transmission media can be classified as guided and unguided. In both cases, communication is in the form of electromagnetic waves. With guided media, the waves are guided along a solid medium, such as copper twisted pair, copper coaxial cable and optical fiber. The atmosphere and outer space are examples of unguided media that provide a means of transmitting electromagnetic signals but do not guide them, this form of transmission is usually referred as wireless transmission.


Guided Transmission Media

In guided transmission media, transmission depend on data rate, bandwidth, distance, medium is point-to-point or multipoint in LAN.

There are mainly three types of guided media used as discussed b…

Basics Of Data Communication: Part 5

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This article will explain, Data Link Control, Error Detection, Flow Control, Error Control Mechanisms etc.



Data Link Control

Data Link Control (DLC) is the service provided by the data link layer of function defined in the Open Systems Interconnection (OSI) model for network communication. The Data Link layer is responsible for providing reliable data transfer across one physical link within the network.

To see the need for data link control, we list some requirements and objectives for effective data communication between two directly connected transmitting-receiving stations. Here is the list of all
Frame Synchronization
Data are sent in blocks called frames. The beginning and end of each frame must be recognizable.

Flow Control
The sending station must not send frames at a rate faster than the receiving station can absorb them.

Error Control
Any bit errors introduced by the transmission system must be corrected.

AddressingOn a multipoint line, such as a local area network (LAN), the identit…

Basics of Data Communication Part: 2

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This article will explain, Data Communication Networking, Protocols and Protocol Architecture.



Data Communication Networking

Data Communication takes place between two devices that are directly connected by some form of point-to-point transmission medium. The devices are very far apart. It would be inordinately expensive if string a dedicated link between two devices which is thousands of miles apart. There is set of devices used to establish such networks. There are following types of networking available:

Wide Area Network (WAN)
Wide area networks have traditionally been considered to be those that cover a large geographical area. Typically, a WAN consists of a number of interconnected switching nodes. Transmission from any one device is routed through these internal nodes to the specific destination device. WAN has been implemented using one of the following technologies:

Circuit Switching
In circuit-switching, this path is decided upon before the data transmission starts. The system de…

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