Data Communication & Networking

Introduction

Data Communication & Networking are changing the way we do business and the way we live. For better business decision we require immediate access to accurate information. Technological advances are making it possible for communication links to carry more & faster signals. When we communicate we share information, this sharing can be local or remote. The term telecommunication which includes telephony, telegraphy & television means communication at a distance (Tele is Greek for far)

Data Communications

Data

Information presented in whatever form is agreed upon by the parties creating and using the data Exchange of data between two devices Via some form of transmission medium such as wire cable Delivery : System must deliver the data to the correct destination. Accuracy: System must deliver the data accurately. Timeliness: Jitter: Refer to the Variation in the packet arrival time For Ex assume that video packet are sent every 30 ms. If some of the pocket arrive with 30 ms delay and others with 40 ms delay, an uneven quality in the video is the result..

Data communication

Fundamental characteristics of data communication

Five Components of Data Communication

Five Components of Data Communication

Message: Information(data) to be communicated Sender : Device that sends the data message. It can be computer, telephone handset, video camera & so on

Receiver: That receive the message . It can be computer, telephone handset, video camera & so on

Transmission medium: Physical path by which a message travels. Ex. Twisted pair, coaxial cable, fiber-optical cable, radio waves.

Protocol: A set of rules that govern data communication without a protocol device may be connected but not communicating, just as speaking French cannot be understand by a person who speak only Japanese

Direction of Data Flow

Data Flow

Simplex

Unidirectional As on a one-way street Ex: Keyboard, Monitor Both transmit and receive possible, but not at the same time Like a one-lane road with two-directional traffic Walkie-talkie Transmit and receive simultaneously Like a two-way street, telephone network Channel capacity must be divided between two directions

Half-duplex

Full-duplex (Duplex)

Network

Network: A set of devices (nodes) connected by communication links Node: Computer, printer, or any device capable of sending and/or receiving data To be considered effective and efficient, a network must meet a number of criteria

Network

Performance : can be measure by transit time & Response time. Transit time is the amount of time required for a message to travel from one device to another.

Response Time: is the elapsed time between an inquiry and response.

Performance depends up number of users ,types of transmissionmedium, capacity of hardware, efficiency of the software

Performance also evaluated using Throughput and Delay Network throughput is the average rate of successful message delivery over a communication channel. The throughput is usually measured in bits per second (bit/s or bps), and sometimes in data packets per second or data packets per time slot.

Network

Reliability : can be measure frequency of failure, the time it takes a link to recover from failure.

Security: It include protecting data from unauthorized access, protecting data from damage and development and implementing policies and procedures for recovery from breaches and data losses.

Uses of Computer NetworksBusiness Applications Home Applications Mobile Users Social Issues

Uses of Computer NetworksBusiness Applications

Many companies have a substantial number of computers the issue here is resource sharing, and the goal is to make all programs, equipment, and especially data available to anyone on the network without regard to the physical location of the resource and the user. An example is having a group of office workers share a common printer, scanners, and CD burners more important, is sharing information

Uses of Computer NetworksBusiness Applications

Most companies have customer records, inventories, accounts receivable, financial statements, tax information, and much more online. If all of its computers went down, a bank could not last more than five minutes. A modern manufacturing plant, with a computer-controlled assembly line, would not last even that long. Even a small travel agency or three-person law firm is now highly dependent on computer networks for allowing employees to access relevant information and documents instantly.

Uses of Computer NetworksBusiness Applications

Most companies have customer records, inventories, accounts receivable, financial statements, tax information, and much more online. If all of its computers went down, a bank could not last more than five minutes. A modern manufacturing plant, with a computer-controlled assembly line, would not last even that long. Even a small travel agency or three-person law firm is now highly dependent on computer networks for allowing employees to access relevant information and documents instantly.

Business Applications of NetworksA

network with two clients and one server.

Business Applications of Networks as Communication Medium A computer network can provide a powerful communication medium among employees. Virtually every company that has two or more computers now has e-mail (electronic mail) Yet another form of computer-assisted communication is videoconferencing A third goal for increasingly many companies is doing business electronically with other companies A fourth goal that is starting to become more important is doing business with consumers over the Internet. Called e-commerce

The

Business Applications of Networks as Communication Mediumclient-server model involves requests and replies.

Home Network Applications

Access to remote information

It can be surfing the World Wide Web for information or just for fun. Information available includes the arts, business, cooking, government, health, history, hobbies, recreation, science, sports, travel, and many others..

Person-to-person communication Interactive entertainment Electronic commerce

Home Network Applications

Person-to-person communication instant messaging, chat room peer-to-peer communication-In this form, individuals who form a loose group can communicate with others in the group Interactive entertainment Electronic commerce

Home Network Applications (2) In

peer-to-peer system there are no fixed clients and servers.

Home Network Applications (3) Some

forms of e-commerce.

Type of Connection

A network is two or more devices connected through link. A link is communication pathway that transfer data from one device to another. Two types connection Point-to-point

Dedicated link between two devices The entire capacity of the channel is reserved Ex) Microwave link, TV remote control

Multipoint also called Multidrop

More than two devices share a single link Capacity of the channel is either

Spatially shared: Several simultaneously Timeshare: Users take turns

Devices

can

use

the

link

Type of Connection

Physical Topology

It refers to the way in which a network is laid out physically. Two or more devices connect to a link; two or more link form a topology. The topology of a network is the geometric representation of the relationship of all the links and linking device to one another. Four basic topologies: Mesh, Star, Bus, Ring

Mesh Topology

Mesh Topology

Every device has a dedicated point-to-point link to every other device.

To find the number of physical link in a fully connected mesh network with n nodes.

Each nodes must be connected to every other nodes. Nodes 1 must be connected to n-1 nodes, nodes 2 connected to n-1 and finally node n must connected to n-1 nodes.

We need n(n-1) physical link. However if each physical link allows communication in both direction we can divide the number of link by 2

A mesh network with n nodes has n(n-1)/2 links.

Mesh TopologyAdvantages:

Use of dedicated links guarantees that each connection can carry its own data load. Thus no traffic problems,

Robust If one link become unusable, it does not incapacitate the entire system.

Security, only intended recipient see the message Easy fault identification & isolation

Disadvantages:

Amount of cabling and the number of port required.Every device must be connected to every device therefore difficult installation/reconfiguration, space, cost

Star Topology

Dedicated point-to-point link only to a central controller, called a hub Devices are not directly linked to one another. Hub acts as an exchange: No direct traffic between devices Advantages: Less expensive, robust, easy to install and reconfigure Disadvantages: dependency of the whole on one single point, the hub Example LAN

Bus Topology

One long cable that links all nodes Nodes are connected to the bus cable by tap and drop line As signal travels along the backbone some of its energy is transferred into heat. Therefore there is limit on the number taps a bus can support and on the distance between those taps Advantages: Easy installation, cheap Disadvantages: Difficult reconfiguration, no fault isolation, a fault or break in the bus stops all transmission

Ring Topology

Dedicated point-to-point link only with the two nodes on each sides A signal is passed

Data Communication & Networking

Oct 26, 2014

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Data Communication & Networking

Introduction

Data Communication & Networking are changing the way we do business and the way we live. For better business decision we require immediate access to accurate information. Technological advances are making it possible for communication links to carry more & faster signals. When we communicate we share information, this sharing can be local or remote. The term telecommunication which includes telephony, telegraphy & television means communication at a distance (Tele is Greek for far)

Data Communications

Data

Information presented in whatever form is agreed upon by the parties creating and using the data Exchange of data between two devices Via some form of transmission medium such as wire cable Delivery : System must deliver the data to the correct destination. Accuracy: System must deliver the data accurately. Timeliness: Jitter: Refer to the Variation in the packet arrival time For Ex assume that video packet are sent every 30 ms. If some of the pocket arrive with 30 ms delay and others with 40 ms delay, an uneven quality in the video is the result..

Data communication

Fundamental characteristics of data communication

Five Components of Data Communication

Five Components of Data Communication

Message: Information(data) to be communicated Sender : Device that sends the data message. It can be computer, telephone handset, video camera & so on

Receiver: That receive the message . It can be computer, telephone handset, video camera & so on

Transmission medium: Physical path by which a message travels. Ex. Twisted pair, coaxial cable, fiber-optical cable, radio waves.

Protocol: A set of rules that govern data communication without a protocol device may be connected but not communicating, just as speaking French cannot be understand by a person who speak only Japanese

Direction of Data Flow

Data Flow

Simplex

Unidirectional As on a one-way street Ex: Keyboard, Monitor Both transmit and receive possible, but not at the same time Like a one-lane road with two-directional traffic Walkie-talkie Transmit and receive simultaneously Like a two-way street, telephone network Channel capacity must be divided between two directions

Half-duplex

Full-duplex (Duplex)

Network

Network: A set of devices (nodes) connected by communication links Node: Computer, printer, or any device capable of sending and/or receiving data To be considered effective and efficient, a network must meet a number of criteria

Network

Performance : can be measure by transit time & Response time. Transit time is the amount of time required for a message to travel from one device to another.

Response Time: is the elapsed time between an inquiry and response.

Performance depends up number of users ,types of transmissionmedium, capacity of hardware, efficiency of the software

Performance also evaluated using Throughput and Delay Network throughput is the average rate of successful message delivery over a communication channel. The throughput is usually measured in bits per second (bit/s or bps), and sometimes in data packets per second or data packets per time slot.

Network

Reliability : can be measure frequency of failure, the time it takes a link to recover from failure.

Security: It include protecting data from unauthorized access, protecting data from damage and development and implementing policies and procedures for recovery from breaches and data losses.

Uses of Computer NetworksBusiness Applications Home Applications Mobile Users Social Issues

Uses of Computer NetworksBusiness Applications

Many companies have a substantial number of computers the issue here is resource sharing, and the goal is to make all programs, equipment, and especially data available to anyone on the network without regard to the physical location of the resource and the user. An example is having a group of office workers share a common printer, scanners, and CD burners more important, is sharing information

Uses of Computer NetworksBusiness Applications

Most companies have customer records, inventories, accounts receivable, financial statements, tax information, and much more online. If all of its computers went down, a bank could not last more than five minutes. A modern manufacturing plant, with a computer-controlled assembly line, would not last even that long. Even a small travel agency or three-person law firm is now highly dependent on computer networks for allowing employees to access relevant information and documents instantly.

Uses of Computer NetworksBusiness Applications

Most companies have customer records, inventories, accounts receivable, financial statements, tax information, and much more online. If all of its computers went down, a bank could not last more than five minutes. A modern manufacturing plant, with a computer-controlled assembly line, would not last even that long. Even a small travel agency or three-person law firm is now highly dependent on computer networks for allowing employees to access relevant information and documents instantly.

Business Applications of NetworksA

network with two clients and one server.

Business Applications of Networks as Communication Medium A computer network can provide a powerful communication medium among employees. Virtually every company that has two or more computers now has e-mail (electronic mail) Yet another form of computer-assisted communication is videoconferencing A third goal for increasingly many companies is doing business electronically with other companies A fourth goal that is starting to become more important is doing business with consumers over the Internet. Called e-commerce

The

Business Applications of Networks as Communication Mediumclient-server model involves requests and replies.

Home Network Applications

Access to remote information

It can be surfing the World Wide Web for information or just for fun. Information available includes the arts, business, cooking, government, health, history, hobbies, recreation, science, sports, travel, and many others..

Person-to-person communication Interactive entertainment Electronic commerce

Home Network Applications

Person-to-person communication instant messaging, chat room peer-to-peer communication-In this form, individuals who form a loose group can communicate with others in the group Interactive entertainment Electronic commerce

Home Network Applications (2) In

peer-to-peer system there are no fixed clients and servers.

Home Network Applications (3) Some

forms of e-commerce.

Type of Connection

A network is two or more devices connected through link. A link is communication pathway that transfer data from one device to another. Two types connection Point-to-point

Dedicated link between two devices The entire capacity of the channel is reserved Ex) Microwave link, TV remote control

Multipoint also called Multidrop

More than two devices share a single link Capacity of the channel is either

Spatially shared: Several simultaneously Timeshare: Users take turns

Devices

can

use

the

link

Type of Connection

Physical Topology

It refers to the way in which a network is laid out physically. Two or more devices connect to a link; two or more link form a topology. The topology of a network is the geometric representation of the relationship of all the links and linking device to one another. Four basic topologies: Mesh, Star, Bus, Ring

Mesh Topology

Mesh Topology

Every device has a dedicated point-to-point link to every other device.

To find the number of physical link in a fully connected mesh network with n nodes.

Each nodes must be connected to every other nodes. Nodes 1 must be connected to n-1 nodes, nodes 2 connected to n-1 and finally node n must connected to n-1 nodes.

We need n(n-1) physical link. However if each physical link allows communication in both direction we can divide the number of link by 2

A mesh network with n nodes has n(n-1)/2 links.

Mesh TopologyAdvantages:

Use of dedicated links guarantees that each connection can carry its own data load. Thus no traffic problems,

Robust If one link become unusable, it does not incapacitate the entire system.

Security, only intended recipient see the message Easy fault identification & isolation

Disadvantages:

Amount of cabling and the number of port required.Every device must be connected to every device therefore difficult installation/reconfiguration, space, cost

Star Topology

Dedicated point-to-point link only to a central controller, called a hub Devices are not directly linked to one another. Hub acts as an exchange: No direct traffic between devices Advantages: Less expensive, robust, easy to install and reconfigure Disadvantages: dependency of the whole on one single point, the hub Example LAN

Bus Topology

One long cable that links all nodes Nodes are connected to the bus cable by tap and drop line As signal travels along the backbone some of its energy is transferred into heat. Therefore there is limit on the number taps a bus can support and on the distance between those taps Advantages: Easy installation, cheap Disadvantages: Difficult reconfiguration, no fault isolation, a fault or break in the bus stops all transmission

Ring Topology

Dedicated point-to-point link only with the two nodes on each sides A signal is passed