1 D ATA C OMMUNICATIONS AND N ETWORKING K ASHIF I HSAN, L ECTURER CS, MIHE

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DATA COMMUNICATIONS AND NETWORKING

KASHIF IHSAN, LECTURER CS, MIHE

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DATA COMMUNICATIONS &

NETWORKING


CONTENTS

Line Configuration

Network Topology

Categories of Networks

Internet & its History


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LINE CONFIGURATION

Line configuration defines the attachment of communication devices to a link.

OR

Line configuration is concerned with the connection of devices to the transmission media.

Line configuration is also referred to as connection.


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LINE CONFIGURATION

A link is a communication medium through which data is communicated between devices.

For communication to occur between two devices, they must be connected to the same link at the same time.


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TYPES OF LINE CONFIGURATION

There are two possible types of line configurations:

1. Point-to-Point Connection

2. Multipoint Connection


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POINT-TO-POINT

A point to point line configuration provides a dedicated link between two communicating devices.

This entire link is reserved only for the communication of these two particular devices, and no other device can use that link.


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POINT-TO-POINT

When you change the television channel by remote control, you are establishing a point-to-point connection between the remote control and the television’s control system.


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POINT-TO-POINT


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MULTIPOINT

A multipoint line configuration is one in which more than two devices share a single link.

This type of connection allows multiple devices (more than two devices) to share a single link.


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MULTIPOINT


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NETWORK TOPOLOGY

The network topology is the shape or the physical connectivity of the network.

Network topology defines the physical structure of the network.


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NETWORK TOPOLOGY

We will discuss the following types of network topology in detail:

Bus Topology

Star Topology

Ring Topology

Mesh Topology


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BUS TOPOLOGY

A bus topology is a multipoint configuration.

One long cable acts as a backbone to connect all the devices in the network.

Devices are connected to the bus by drop-line and tap.


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BUS TOPOLOGY

Drop-line: It is a connection running between the device and main cable.

Tap: It is a connector that either splices into the main cable or punctures the cable to create contact with the metallic core.


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BUS TOPOLOGY


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BUS TOPOLOGY

Advantage:

Ease of installation since less cabling is required.

Disadvantages:

Network won’t transmit correctly if even one node on the network is malfunctioning.

Difficulty in fault isolation as due to fault, the whole network may be down.


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STAR TOPOLOGY

In star topology, each device has a dedicated point-to-point link only to the central controller, generally called a HUB.

In star topology, communication is with a central HUB that resend the message either to all the computers (in a broadcast star network) or only to the destination computer (in a switch star network).


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STAR TOPOLOGY

The devices are not directly linked to one another.

The controller acts as an exchange, if one device want to send data to another, it send the data to the controller, which then sends the data to the other connected device.


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STAR TOPOLOGY


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STAR TOPOLOGY

Advantages:

Better performance: Star topology prevents the passing of data packets through an excessive number of nodes. At most, 3 devices and 2 links are involved in any communication between any two devices.

Benefits from centralization: Centralization also allows the inspection of traffic through the network. This facilitates analysis of the traffic and detection of suspicious behavior.


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STAR TOPOLOGY

Advantages:

No disruptions to the network when connecting or removing devices from the network.

Disadvantages:

High dependence of the system on the functioning of the central hub.

Failure of the central hub results in the network being inoperable.


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RING TOPOLOGY

A topology where each device has a dedicated point-to-point line configuration (connection) only with the two devices on either side of it, thus forming a single continuous pathway for signals through each device – a ring.

Each device in the ring incorporates a repeater.


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RING TOPOLOGY


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RING TOPOLOGY

Advantages:

Very orderly network where every device has the opportunity to transmit.

Performs better than a bus topology under heavy network load.

Does not require network server to manage the connectivity between the computers.


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RING TOPOLOGY

Disadvantages:

A break in the ring (a disabled device) can cause the whole network disabled.

Moves, adds and changes of devices can affect the network.


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MESH TOPOLOGY

A topology where every device has a dedicated point-to-point link to every other device.

We need n(n-1) physical link, however, if physical link allow communication in both direction (duplex mode), we can divide the number of links by 2.


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MESH TOPOLOGY

In other words we can say that in mesh topology we need n(n-1)/2 duplex mode links.


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MESH TOPOLOGY


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MESH TOPOLOGY

Advantages:

The use of dedicated links guarantees that each connection can carry its own load.

Robust (strong & healthy; can recover fast from failed state).

Evidence of privacy and security.

Ease in fault identification and fault isolation.


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MESH TOPOLOGY

Disadvantages:

Difficulty in installation and reconfiguration.

Bulk of wiring can be greater than the available space.

Hardware requirements to connect each link is relatively expensive.


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CATEGORIES OF NETWORKS

Networks are categorized into three main categories which are as follows:

LAN (Local Area Network)

MAN (Metropolitan Area Network)

WAN (Wide Area Network)


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CATEGORIES OF NETWORKS


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LAN (LOCAL AREA

NETWORK)

A local area network operate within a limited geographic area.

A networked office building, school, or home usually contains a single LAN, though sometimes one building may contain a few small LANs (perhaps one per room).

LANs are typically owned, controlled and managed by a single person or organization.


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LAN REQUIREMENTS

It has two main requirements:

Hardware Requirements

Software Requirements

Network hardware includes NIC/Network Adapter/LAN Card, Hub/Switch, Cable, Connectors (RJ-45).

Network software includes protocols.


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NIC/LAN CARD


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CABLE & RJ-45 CONNECTOR


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LAN CHARACTERISTICS

It is a high capacity network (230 Kbps to 10 Gbps).

It is local (works within a finite distance in a limited geographic area such as an office or a building).

It usually uses cable but may use radio waves, infrared or microwaves.

It is normally used by a single organization.


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MAN (METROPOLITAN AREA NETWORK)

It is a high speed network which spans city distances. OR

It may be a single network such as cable television network. OR

It may be a means of connecting a number of LANs into a larger network, so that the resources may be shared LAN-to-LAN.


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MAN (METROPOLITAN AREA NETWORK)


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A metropolitan area network may be owned by a private company, or it may be a service provided by a public company, such as a local telephone company.

Many telephone companies provide a popular MAN service called Switched Multi-megabit Data Service (SMDS). It is a service for handling high-speed communication for metropolitan area network.


41MAN (METROPOLITAN AREA NETWORK)

WAN (WIDE AREA NETWORK)

A wide area network (WAN) provides long-distance transmission of data, image, audio, and video information over large geographic areas that may comprise a country, a continent, or even the whole world.

The Internet is the world’s largest WAN.


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43WAN (WIDE AREA NETWORK)

Characteristics:

They use data lines which belong to a third party service provider such as the telephone company. They require special interfaces to the data lines such as synchronous modems & routers.

Routing technology is a crucial component of a WAN. Routers decide how a packet should be sent in order that it arrives at its intended destination


44WAN (WIDE AREA NETWORK)

THE INTERNET

An internet (note the lowercase letter i) is two or more networks that can communicate with each other.

The term internet (lowercase i) should not be confused with the Internet (uppercase I).

The first is a generic term used to mean an interconnection of networks.

The second is the name of a specific world wide network.


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THE INTERNET

The most notable internet is called Internet (uppercase letter I), in which connect more than hundreds of thousands interconnected networks.

Internet simply called “net” is a world wide system of computer networks.


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THE INTERNET

Every computer on the net has a unique Internet address or IP address (similar to telephone address), which can be accessed any other computer by dialing to the other IP address.


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HISTORY OF INTERNET

The extraordinary communication system “Internet” came into being in 1969.

In mid-1960, mainframe computers in research organization were stand-alone devices.

Computers from different manufacturers were unable to communicate with one another.

The Advanced Research Project Agency (ARPA) in the Department of Defense was interesting in in finding a way to connect computers.


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In 1967, at an Association for Computing Machinery (ACM) meeting, ARPA presented its ideas for ARPANET, a small network connected computes.

The basic purpose was to create a network that allows the researchers of one university to be able to talk or share their research to the researchers of other university.


49HISTORY OF INTERNET

The network was designed to work without centralized control.

This means if one portion of network fails, the remaining portion will be able to route packets from sender to receiver through an alternate path.

The second benefits of ARPANET was that, messages could continue functionality, If one portion of network is destroyed in disaster or in military attack.



Internet has linked numerous LANs into huge network. The LANs and computers connected to internet is maintained by Internet Service Providers (ISPs), who sells internet services to people.

Today most end users who want Internet connection use the services of ISPs.

There are International ISPs, National ISPs, Regional ISPs and Local ISPs.



The International ISPs connect nations together.

The National ISPs are backbone networks created and maintained by specialized companies.

The Regional ISPs are smaller ISPs that are connected to one or more national ISPs.

The Local ISPs provide direct services to the end users.





The End

of

Chapter # 02


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1 D ATA C OMMUNICATIONS AND N ETWORKING K ASHIF I HSAN, L ECTURER CS, MIHE