Presentation is loading. Please wait.

Presentation is loading. Please wait.

Unit 5 TelecommunicationsAndNetworks. Contents Telecommunication Alternatives Telecommunication Alternatives Telecommunication model Telecommunication.

Similar presentations


Presentation on theme: "Unit 5 TelecommunicationsAndNetworks. Contents Telecommunication Alternatives Telecommunication Alternatives Telecommunication model Telecommunication."— Presentation transcript:

1 Unit 5 TelecommunicationsAndNetworks

2 Contents Telecommunication Alternatives Telecommunication Alternatives Telecommunication model Telecommunication model Types of Telecommunication Networks Types of Telecommunication Networks Telecom media Telecom media Network topologies Network topologies Network protocols Network protocols

3 Telecommunication Exchange of information in any form Exchange of information in any form voice, voice, data, data, text, text, image, image, audio,video audio,video

4 Major trends in Technology Industry Trend Industry Trend Technology trend Technology trend Application trend Application trend

5 Industry trend Towards more competitive vendors,carriers,alliances and network services, accelerated by deregulation and growth of Internet. Towards more competitive vendors,carriers,alliances and network services, accelerated by deregulation and growth of Internet.

6 Technology Trend Towards extensive use of Internet, digital fiber-optics andwireless technology to create high- speed global networks of voice, data, images etc Towards extensive use of Internet, digital fiber-optics andwireless technology to create high- speed global networks of voice, data, images etc

7 Application Trends Towards the pervasive use of Internet, enterprise intranets and inter-organisation extranets to support electronic business and e-com. Towards the pervasive use of Internet, enterprise intranets and inter-organisation extranets to support electronic business and e-com.

8 Major business values from Internet Generates now revenue resources Generates now revenue resources Reduce cost of transaction Reduce cost of transaction Attract new customers Attract new customers Increase loyalty of existing customers Increase loyalty of existing customers Develop new information-based products Develop new information-based products Develop web-based markets Develop web-based markets

9 Network Alternatives Networks internet, intranet,extranet Networks internet, intranet,extranet Media Twisted-pair, coaxial cable,fiber-optics Media Twisted-pair, coaxial cable,fiber-optics Processors Modems,multiplexes,switches Processors Modems,multiplexes,switches Software Operating-systems Software Operating-systems Channels Analog/Digital, Switched/Non switched Channels Analog/Digital, Switched/Non switched Topology Star, Ring, Bus topology, TCP/IP Topology Star, Ring, Bus topology, TCP/IP architecture architecture

10 Network Model fig 6.10 pg 184 PCs PCs Telecommunication Processors Telecommunication Processors Telecommunication Channels Telecommunication Channels Telecommunication Software Telecommunication Software

11 Applications of telecommunications

12 Types of Telecommunication Networks LAN – Local Area Networks LAN – Local Area Networks WAN- Wide Area Networks WAN- Wide Area Networks Client/Server Networks Client/Server Networks Network Computing Network Computing Peer-to-peer Networks Peer-to-peer Networks

13 Local Area Network It connects computers and other information processing devices within a limited physical area It connects computers and other information processing devices within a limited physical area Eg Office, Classroom in a building Eg Office, Classroom in a building Each PC has a circuit board called a Network Interface Card Each PC has a circuit board called a Network Interface Card A powerful microcomputer of large disk capacity is a network server A powerful microcomputer of large disk capacity is a network server Network Server contains a N/w Operating System which distributes copies of Data Files to other computers in the network Network Server contains a N/w Operating System which distributes copies of Data Files to other computers in the network

14 Telecommunication Media Telephone Wiring Telephone Wiring Coaxial Cable Coaxial Cable Wireless Radio systems Wireless Radio systems Infrared systems Infrared systems

15 Connection equipment The primary hardware set up in local area networks is: The primary hardware set up in local area networks is: Repeaters, used to refresh a signal Repeaters, used to refresh a signal Repeaters Hubs, used for connecting multiple hosts together Hubs, used for connecting multiple hosts together Hubs Bridges, used for linking local area networks of the same type Bridges, used for linking local area networks of the same type Bridges Switches, used for linking various elements while they divide up the network Switches, used for linking various elements while they divide up the network Switches Gateways, used for linking local area networks of different types Gateways, used for linking local area networks of different types Gateways Routers, used for linking numerous local area networks so as to allow data to travel optimally between networks Routers, used for linking numerous local area networks so as to allow data to travel optimally between networks Routers Bridge/routers, which join the features of a router and a bridge Bridge/routers, which join the features of a router and a bridge Bridge/routers

16 Ethernet: The Basis for Every Network Setting up your wired LAN (Local Area Network) is as simple as buying the components and linking them together with Ethernet cable. Well, almost that simple. There are several approaches you could take: 1. Set up a wired network in a single room in your home using short, prepackaged Ethernet cables. 2. Purchase bulk cable and connectors and run Ethernet cables from room to room. 3. Hire a professional to wire your home with in-wall Ethernet cable. Once you have your wired network in place, it’s easy to add a wireless access point to allow wireless networking as well. Your network is never set in stone — you can always add components and technology to make it fit your lifestyle. Setting up your wired LAN (Local Area Network) is as simple as buying the components and linking them together with Ethernet cable. Well, almost that simple. There are several approaches you could take: 1. Set up a wired network in a single room in your home using short, prepackaged Ethernet cables. 2. Purchase bulk cable and connectors and run Ethernet cables from room to room. 3. Hire a professional to wire your home with in-wall Ethernet cable. Once you have your wired network in place, it’s easy to add a wireless access point to allow wireless networking as well. Your network is never set in stone — you can always add components and technology to make it fit your lifestyle.

17 A Typical wired network

18 Wide Area Network Wide Area Network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries ). Wide Area Network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries ).computer networkcomputer network This is in contrast with This is in contrast with personal area networks (PANs), personal area networks (PANs), personal area networks personal area networks local area networks (LANs), local area networks (LANs),local area networkslocal area networks campus area networks (CANs), or campus area networks (CANs), or campus area networks campus area networks metropolitan area networks (MANs) metropolitan area networks (MANs)metropolitan area networksmetropolitan area networks which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. The largest and most well-known example of a WAN is the Internet.Internet

19 ACCOUNTING INFORMATION SYSTEMS: A DATABASE APPROACH by: Uday S. Murthy, Ph.D., ACA and S. Michael Groomer, Ph.D., CPA, CISA https:/.../books/primerprev/chapter s/ch2.htm https:/.../books/primerprev/chapter s/ch2.htm

20 Client /Server networks Client-server describes the relationship between two computer programs in which one program, the client program, makes a service request to another, the server program. Standard networked functions such as exchange, web access and database access, are based on the client-server model. Client-server describes the relationship between two computer programs in which one program, the client program, makes a service request to another, the server program. Standard networked functions such as exchange, web access and database access, are based on the client-server model. For example, a web browser is a client program at the user computer that may access information at any web server in the world. For example, a web browser is a client program at the user computer that may access information at any web server in the world.web browserweb browser To check your bank account from your computer, a web browser client program in your computer forwards your request to a web server program at the bank. That program may in turn forward the request to its own database client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned to the bank database client, which in turn serves it back to the web browser client in your personal computer, which displays the information for you To check your bank account from your computer, a web browser client program in your computer forwards your request to a web server program at the bank. That program may in turn forward the request to its own database client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned to the bank database client, which in turn serves it back to the web browser client in your personal computer, which displays the information for you

21 contd To check your bank account from your computer, a web browser client program in your computer forwards your request to a web server program at the bank. To check your bank account from your computer, a web browser client program in your computer forwards your request to a web server program at the bank. That program may in turn forward the request to its own database client program that sends a request to a database server at another bank computer to retrieve your account balance. That program may in turn forward the request to its own database client program that sends a request to a database server at another bank computer to retrieve your account balance. The balance is returned to the bank database client, which in turn serves it back to the web browser client in your personal computer, which displays the information for you The balance is returned to the bank database client, which in turn serves it back to the web browser client in your personal computer, which displays the information for you

22 Peer-to-Peer Networks  In peer-to-peer architectures, each host or instance of the program can simultaneously act as both a client and a server, and each has equivalent responsibilities and status.  Both client-server and peer-to-peer architectures are in wide usage today.

23 Diagram of network

24 Peer-to-Peer Networks Peer-to-peer networks allow you to connect two or more computers in order to pool their resources. Individual resources such as disk drives, CD-ROM drives, scanners and even printers are transformed into shared resources that are accessible from each of the computers. Peer-to-peer networks allow you to connect two or more computers in order to pool their resources. Individual resources such as disk drives, CD-ROM drives, scanners and even printers are transformed into shared resources that are accessible from each of the computers. Unlike client-server networks, where network information is stored on a centralized file server computer and then made available to large groups of workstation computers, the information stored over a peer-to-peer network is stored locally on each individual computer. Since peer-to-peer computers have their own hard disk drives that are accessible and sometimes shared by all of the computers on the peer-to-peer network, each computer acts as both a client (or node) and a server (information storage). In the diagram below, three peer-to-peer workstations are shown. Although not capable of handling the same rate of information flow that a client-server network would, all three computers can communicate directly with each other and share each other's resources. Unlike client-server networks, where network information is stored on a centralized file server computer and then made available to large groups of workstation computers, the information stored over a peer-to-peer network is stored locally on each individual computer. Since peer-to-peer computers have their own hard disk drives that are accessible and sometimes shared by all of the computers on the peer-to-peer network, each computer acts as both a client (or node) and a server (information storage). In the diagram below, three peer-to-peer workstations are shown. Although not capable of handling the same rate of information flow that a client-server network would, all three computers can communicate directly with each other and share each other's resources.

25 Example of P2P N/W

26 Twisted-pair wire

27 Twisted pair wire Twisted pair wire is the copper wire used to connect telephone devices. The wire is twisted to enhance signal transmission relative to straight wire. Twisted pair wire is the copper wire used to connect telephone devices. The wire is twisted to enhance signal transmission relative to straight wire. Twisted pair wire can be either shielded or unshielded. Twisted pair wire can be either shielded or unshielded. Shielded twisted pair permits higher data transmission speed and is less susceptible to interference, but is also more expensive than unshielded. Shielded twisted pair permits higher data transmission speed and is less susceptible to interference, but is also more expensive than unshielded. Unshielded twisted pair is more common in homes and businesses. Unshielded twisted pair is more common in homes and businesses.

28 Coaxial cables Coaxial cables (or simply coax) are used for cable television and to connect a video cassette recorder to a television. Coaxial cables (or simply coax) are used for cable television and to connect a video cassette recorder to a television. Coax cables comprise a number of insulated wires inside a thick (usually black) insulated sheathing. Coax cables comprise a number of insulated wires inside a thick (usually black) insulated sheathing. Relative to twisted pair, coax cables are capable of far higher transmission speeds and are also less susceptible to electromagnetic interference. Relative to twisted pair, coax cables are capable of far higher transmission speeds and are also less susceptible to electromagnetic interference.

29 Fiber optic cables Fiber optic cables carry only digital signals and can carry signals at very high speeds. Fiber optic cables carry only digital signals and can carry signals at very high speeds. Data transmission on fiber optic cables is in the form of light pulses. Data transmission on fiber optic cables is in the form of light pulses. Provide much larger transmission capacity, or bandwidth, than twisted pair wire or coax cables. Since transmissions along a fiber optic line occur using pulses of light, this medium is essentially impervious to interference from electromagnetic sources. Provide much larger transmission capacity, or bandwidth, than twisted pair wire or coax cables. Since transmissions along a fiber optic line occur using pulses of light, this medium is essentially impervious to interference from electromagnetic sources. However, fiber optic cables are more fragile than twisted pair and coax cables and are usually more expensive. However, fiber optic cables are more fragile than twisted pair and coax cables and are usually more expensive.

30 wireless transmission links The first of these wireless transmission links is infrared transmission, which involves the movement of extremely short wavelengths in a straight line. The first of these wireless transmission links is infrared transmission, which involves the movement of extremely short wavelengths in a straight line. Infrared transmission, so called because its range is below the visible spectrum, is the transmission technology used for remote control units on audio and video equipment. As you may have experienced, infrared waves have a very limited range and cannot penetrate solid objects. Whereas infrared transmission is used only for very short distances, microwave and satellite transmission are used to cover long distances. Infrared transmission, so called because its range is below the visible spectrum, is the transmission technology used for remote control units on audio and video equipment. As you may have experienced, infrared waves have a very limited range and cannot penetrate solid objects. Whereas infrared transmission is used only for very short distances, microwave and satellite transmission are used to cover long distances.

31 Cable Types

32

33 Microwave Transmission Microwaves are very high frequency (above 1 gigahertz) radio waves that travel along a "line of sight" path. Since microwaves travel in a straight line (hence the term "line of sight"), repeater stations must be placed every 50 miles or so to relay the signal from one point to the next. Microwave transmission is also very high bandwidth and carries over half of all telephone and television traffic in the Microwaves are very high frequency (above 1 gigahertz) radio waves that travel along a "line of sight" path. Since microwaves travel in a straight line (hence the term "line of sight"), repeater stations must be placed every 50 miles or so to relay the signal from one point to the next. Microwave transmission is also very high bandwidth and carries over half of all telephone and television traffic in the

34 Satellite Transmission The final "through the air" transmission link option is satellites. The final "through the air" transmission link option is satellites. Radio signals are sent from ground stations to satellites which then transmit the signals to other ground stations at distant locations. The satellites are usually in a geosynchronous (or geostationary) orbit which means that they rotate at the same speed as the earth's rotation speed such that they always appear above the same point relative to the earth's surface. Radio signals are sent from ground stations to satellites which then transmit the signals to other ground stations at distant locations. The satellites are usually in a geosynchronous (or geostationary) orbit which means that they rotate at the same speed as the earth's rotation speed such that they always appear above the same point relative to the earth's surface. One communication satellite in a geosynchronous orbit can cover about 30% of the earth's surface. One communication satellite in a geosynchronous orbit can cover about 30% of the earth's surface. Needless to say, leasing time on a satellite link can be very expensive due to the high cost of launching and operating a communications satellite. Needless to say, leasing time on a satellite link can be very expensive due to the high cost of launching and operating a communications satellite.

35

36 Application layer The application layer is the highest layer in the OSI model and is what the user sees (at both the sending and receiving ends of the communication network). It defines the way the user's application program interacts with the network. The application program could be either electronic mail, database management, or a terminal emulation program (for connecting to a mainframe computer system). It is in the application layer that the user's message is converted from human readable form to computer readable form with the message header indicating the sender and intended receiver of the message The application layer is the highest layer in the OSI model and is what the user sees (at both the sending and receiving ends of the communication network). It defines the way the user's application program interacts with the network. The application program could be either electronic mail, database management, or a terminal emulation program (for connecting to a mainframe computer system). It is in the application layer that the user's message is converted from human readable form to computer readable form with the message header indicating the sender and intended receiver of the message

37 Presentation layer Presentation layer The presentation layer defines the way that data is formatted, presented, converted, and coded. The presentation layer defines the way that data is formatted, presented, converted, and coded. The presentation layer ensures that the message is transmitted in a language that the receiving computer can understand (often ASCII -- American Standard Code for Information Interchange). The presentation layer ensures that the message is transmitted in a language that the receiving computer can understand (often ASCII -- American Standard Code for Information Interchange). If necessary, or as directed by the user, the message is also compressed and encrypted at this stage. If necessary, or as directed by the user, the message is also compressed and encrypted at this stage.

38 Session layer The session layer coordinates communication between the sender and receiver. The session layer coordinates communication between the sender and receiver. This layer maintains the session for as long as it is needed, performing security, logging, and any administrative functions that are needed. It is in the session layer that the mode of communication is established This layer maintains the session for as long as it is needed, performing security, logging, and any administrative functions that are needed. It is in the session layer that the mode of communication is established Full duplex where both parties in the communication can send and receive messages simultaneously, or Full duplex where both parties in the communication can send and receive messages simultaneously, or half duplex where the parties must take turns communicating. All of these details are recorded and placed into a "session header" for the session. half duplex where the parties must take turns communicating. All of these details are recorded and placed into a "session header" for the session.

39 Transport layer The transport layer, layer 4, defines protocols for message structure and supervises the validity of the transmission by performing error checking. The transport layer, layer 4, defines protocols for message structure and supervises the validity of the transmission by performing error checking. In effect, the transport layer protects the data being transmitted. In effect, the transport layer protects the data being transmitted.

40 Network layer The third layer, the network layer, defines protocols for data routing to ensure that the data arrives at the correct destination node. The third layer, the network layer, defines protocols for data routing to ensure that the data arrives at the correct destination node. It selects a route for the message, using protocols such as TCP/IP (transmission control protocol/internet protocol), or IPX/SPX which is the protocol for Novell networks. It selects a route for the message, using protocols such as TCP/IP (transmission control protocol/internet protocol), or IPX/SPX which is the protocol for Novell networks. Routers, discussed above, are used at the network layer. Routers, discussed above, are used at the network layer. The data are formed into packets and a header is added that contains the sequence and number of packets and the network address of the destination. The data are formed into packets and a header is added that contains the sequence and number of packets and the network address of the destination.

41 Data-link layer data-link layer, validates the integrity of the flow of data between nodes. data-link layer, validates the integrity of the flow of data between nodes. This validation is performed by synchronizing blocks of data and controlling the flow of data. In this manner, the data-link layer supervises the transmission. This validation is performed by synchronizing blocks of data and controlling the flow of data. In this manner, the data-link layer supervises the transmission. It confirms the checksum and then addresses and duplicates the packets. It confirms the checksum and then addresses and duplicates the packets. The data-link layer keeps a copy of each packet until it receives confirmation from the next point along the transmission route that the packet has been received. Bridges are used at the data-link layer The data-link layer keeps a copy of each packet until it receives confirmation from the next point along the transmission route that the packet has been received. Bridges are used at the data-link layer

42 Physical layer Finally, the physical layer, is the actual transmission hardware or link along which the messages physically pass. It is only along layer 1 that messages physically move from the origin to the destination. Finally, the physical layer, is the actual transmission hardware or link along which the messages physically pass. It is only along layer 1 that messages physically move from the origin to the destination. If phone lines are being used, then it is the physical layer that actually converts the digital signals into analog signals so that they can be carried on the phone line. Intermediate nodes along the transmission path verify the checksum and might reroute the message in light of congestion in the network. If phone lines are being used, then it is the physical layer that actually converts the digital signals into analog signals so that they can be carried on the phone line. Intermediate nodes along the transmission path verify the checksum and might reroute the message in light of congestion in the network.

43 At the receiving end At the receiving end, the message passes through the same seven layers, in reverse. At the receiving end, the message passes through the same seven layers, in reverse. The physical layer reconverts the analog signals into digital form (bits). The physical layer reconverts the analog signals into digital form (bits). The data-link layer recomputes the checksum, confirms arrival, and logs in the packets. The data-link layer recomputes the checksum, confirms arrival, and logs in the packets. The network layer recounts each packet for security and billing purposes. The network layer recounts each packet for security and billing purposes. The transport layer again recalculates the checksum and rebuilds the message segments. The transport layer again recalculates the checksum and rebuilds the message segments. The session layer holds the parts of the message until the message is complete and then sends it to the next layer. The session layer holds the parts of the message until the message is complete and then sends it to the next layer. If the message was compressed, the presentation layer expands it, and if the message had been encrypted it is decrypted at this stage. If the message was compressed, the presentation layer expands it, and if the message had been encrypted it is decrypted at this stage. Finally, the application layer reconverts the bits into readable characters and directs the data to the appropriate application (e.g., ). Finally, the application layer reconverts the bits into readable characters and directs the data to the appropriate application (e.g., ).

44 Network topologies The three network topologies are bus, ring, and star. Bus networks The three network topologies are bus, ring, and star. Bus networks The actual connection is by means of a "tap" which allows the device to listen to the transmissions along the bus The actual connection is by means of a "tap" which allows the device to listen to the transmissions along the bus

45

46 Bus Topology Bus networks use the Ethernet protocol which is capable of transferring data at the rate of 10 megabits per second (mbps) to 100 mbps. Bus networks use the Ethernet protocol which is capable of transferring data at the rate of 10 megabits per second (mbps) to 100 mbps. Devices connected via Ethernet links use a technique called carrier sense multiple access/collision detection (CSMA/CD) to communicate. Devices connected via Ethernet links use a technique called carrier sense multiple access/collision detection (CSMA/CD) to communicate. This convention allows multiple access to the bus network such that any node can essentially broadcast a message over the bus to another node. Every node constantly monitors the bus to detect messages intended for itself (hence the terms "carrier sense" and "multiple access"). This convention allows multiple access to the bus network such that any node can essentially broadcast a message over the bus to another node. Every node constantly monitors the bus to detect messages intended for itself (hence the terms "carrier sense" and "multiple access"). If two nodes attempt to transmit messages simultaneously to each other or to the same node a collision occurs. The nodes involved in a collision wait for a random period of time until one of them tries to send the message again. If two nodes attempt to transmit messages simultaneously to each other or to the same node a collision occurs. The nodes involved in a collision wait for a random period of time until one of them tries to send the message again.

47

48 Ring topology In a ring LAN, each device is connected to a common circular loop (cable). In a ring LAN, each device is connected to a common circular loop (cable). The physical connection to the ring is by means of a "repeater," as depicted in the figure. The physical connection to the ring is by means of a "repeater," as depicted in the figure. It is like a circular rapid transit system in which the train arrives at each station along the ring, dropping off and picking up passengers at each station. In similar fashion, each node in a ring network is polled to determine whether it has any messages to send. It is like a circular rapid transit system in which the train arrives at each station along the ring, dropping off and picking up passengers at each station. In similar fashion, each node in a ring network is polled to determine whether it has any messages to send. Messages typically move in one direction around the ring Messages typically move in one direction around the ring

49

50 Star topology The final LAN configuration is the star in which one computer acts as the "host" computer to which all other computers and devices are connected. The central host computer is also referred to as the "hub." The final LAN configuration is the star in which one computer acts as the "host" computer to which all other computers and devices are connected. The central host computer is also referred to as the "hub." All messages are routed through the host. Messages are channeled by the host to the intended node in a process referred to as network switching. All messages are routed through the host. Messages are channeled by the host to the intended node in a process referred to as network switching. Star networks use a significant amount of cable since each node must have its own direct connection to the central host computer. Star networks use a significant amount of cable since each node must have its own direct connection to the central host computer. The most critical link in a star network is the central host computer; if it breaks down then the entire network becomes inoperative. The most critical link in a star network is the central host computer; if it breaks down then the entire network becomes inoperative. By contrast, bus networks are the most fault tolerant because a defective device does not cripple the entire network By contrast, bus networks are the most fault tolerant because a defective device does not cripple the entire network


Download ppt "Unit 5 TelecommunicationsAndNetworks. Contents Telecommunication Alternatives Telecommunication Alternatives Telecommunication model Telecommunication."

Similar presentations


Ads by Google