Computer networks
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The document discusses computer networks, focusing on their definition, uses, types, and data transmission modes. It describes how networks enable sharing of hardware, software, files, and internet connections, and details various network architectures like client-server, peer-to-peer, and point-to-point. Additionally, it covers network topologies, types including LAN, WAN, and MAN, and explains communication methods through telephone networks such as DSL and ISDN.
Computer networks
- 1. Computer Networks Ch:5 Samina Khan FAZAIA DEGREE COLLEGE RISALPUR
- 2. Contents 1. Introduction to networks – Computer network – Uses of networks – Data transmission modes – Network architecture – Types of network architecture 2. Types of networks 3. Communication over networks
- 3. Computer network • A computer network is a set of computers that are connected together so that they can share information and resources.
- 5. Uses of networks • Hardware sharing • Software sharing • File sharing • Internet sharing
- 6. Hardware sharing • Networks allow sharing of computer hardware such as hard disk and printer. • A hard disk can be attached to server to share it with other network users. • A single hard disk can provide storage space to many computers. • Similarly a single printer can be shared among many computers.
- 8. Software sharing • Application software can be installed on server and shared over the network. • There is no need to install it on every computer.
- 9. File sharing • We can easily share files with other user over the network. • A user can place file in a shared location on one computer and make it available to other users. • User can access, modify and view information stored on another computer in the network.
- 12. Internet sharing • A single high speed internet can be shared with all the users over the network. • There is no need to provide separate internet connection to every computer.
- 15. Data transmission modes Simplex Half duplex Full duplex
- 16. Simplex Transmission Mode • Provides data transmission in only one direction. • One end is the sender and other is receiver. • Transmission of data from keyboard to CPU or from CPU to printer is always one direction. • Examples: Radio and television transmission.
- 18. Half Duplex Transmission Mode • Send and receive data in both direction but not simultaneously. • This kind of transmission can be seen in ATM machines.
- 20. Full Duplex Transmission Mode • Transmit information in both direction simultaneously. • Full-duplex transmission mode are communication between computers in a network and communication over telephone line.
- 23. Network architecture • Layout of network • It consists of computers, communication devices, software, wired or wireless transmission of data and connectivity between components.
- 24. Types of network architecture • Client server network • Peer to peer network • Point-to-point network
- 25. Client/ server network • A client/server network is a system where one or more computers called clients connect to a central computer named a server to share or use resources. • In a client and server network, server shares its resources such as hard disk, printers and Internet connection with client computers.
- 26. Characteristics of client/server network • It can be small as two computers and it can have hundreds and even thousands of computers as well. • It provides centralized security to ensure that resources are not accessed by unauthorized users. • Network administrator is responsible for sharing resources, creating user accounts and assigning privileges to all the users of the network.
- 28. Peer to peer network • In a P2P network, the "peers" are computer systems which are connected to each other via the Internet. • Files can be shared directly between systems on the network without the need of a central server. • Each computer on a P2P network becomes a file server as well as a client.
- 29. Characteristics of Peer-to Peer Network • Each computer play the role of server, client or both at the same time. • Suitable for small number of users, ranging between two to ten computers. Large Peer-to-Peer networks become difficult to manage. • It doesn’t provide centralized security.
- 31. Point to point network • A point-to-point connection refers to a communications connection between two communication end points or nodes. • Large networks that connect cities and countries.
- 32. Characteristics of Point-to-Point Network • Used for long distance communication. • There may be different paths for transmission of information.
- 34. TYPES OF NETWORK
- 35. Types of networks based on geographical area • LAN(Local Area Network) • MAN(Metropolitan Area Network) • WAN(Wide Area Network)
- 36. LAN(Local Area Network) • LAN covers a limited area, ranging from a small office to a campus or nearby buildings. • Examples: Network within a school, college, organization, hospital etc.
- 37. Characteristics of LAN • Restricted to a limited area. • Data transmission speed is fast. • Data communication problems rarely occur. • Transmission medium is owned by the user organization.
- 39. WAN(Wide Area Network) • Spans a large geographical area, connecting several locations of an organization across cities, countries and continents. • Example: Internet
- 40. MAN(Metropolitan Area Network) • Falls between LAN and WAN. • It spans area larger than a LAN but smaller than a WAN. • Example: Network used by telecommunicating companies for providing Cable TV and Internet services.
- 42. PAN(Personal Area Network) • A PAN is a computer network for interconnecting electronic devices centered on an individual person's workspace. • A PAN provides data transmission among devices such as computers, smart phones, tablets and personal digital assistants. • It can be wired( USB & FireWire technologies) or wireless(Bluetooth or infrared connection). • E.g Bluetooth network
- 45. Internet • Internet is the largest computer network that connects million of computers all over the world. • Computers on the internet are connected together using telephone lines, fiber optics or wireless signals. • Each computer on the internet has an IP address. • IP stands for internet protocol. It identifies each computer on the internet with its location.
- 46. • World Wide Web(WWW) is the most popular and widely used system to access the internet. • It is a collection of websites available on the internet. • Web browser is used to access websites. • We enter the URL into a browser to access a website.
- 47. Network topology • The physical arrangement of network nodes is called network topology. • A node represent a computer or a network device.
- 48. TYPES OF NETWORK TOPOLOGIES
- 49. Types of network topologies • Bus topology • Ring topology • Star topology • Mesh topology
- 50. Bus Topology • A bus topology is a topology for a Local Area Network (LAN) in which all the nodes are connected to a single cable. • The cable to which the nodes connect is called a "backbone". If the backbone is broken, the entire segment fails.
- 52. Advantages of bus topology • Lowest cost due to short cable length. • Easy to add new computers. • Easy to setup. • Suitable for small networks.
- 53. limitations • If the backbone is broken, the entire segment fails. • Difficult to detect and fix faults.
- 54. Ring Topology • Shaped just like a ring. • In a ring topology, all devices in the network are connected via a cable that loops in a logical ring or circle. • All the messages travel in the same direction.
- 56. Advantages of Ring topology • Managing is easier as to add or remove a device from the topology only two links are required to be changed. • Server or switch is not required to manage network. • All computers have equal opportunity to transmit data.
- 57. Limitations • A link failure can fail the entire network. • Detection of fault is difficult. • Data traffic issues, since all the data is circulating in a ring.
- 58. Star topology • In a star topology each device in the network is connected to a central device called hub/switch. • If one device wants to send data to other device, it has to first send the data to hub and then the hub/switch transmit that data to the designated device. • A switch can connect 4, 8, 16,24 or 32 nodes. • A switch can be connected to another switch to expand network.
- 60. Advantages of Star topology • Easy fault detection • Provides fast communication. • Failure of one node doesn’t stop functioning of the entire network.
- 61. Limitations of star topology • If hub goes down everything goes down, none of the devices can work without hub. • More cables are required. • Costly to implement.
- 62. Mesh Topology • In a Mesh topology, all the network nodes/devices are connected to all the other nodes/devices. • Number of links in a mesh topology of n devices would be n(n-1)/2. • Message sent on a Mesh can take any possible path from source to destination. • Not commonly used since it is costly.
- 64. Advantages of Mesh topology • Most reliable topology. • No data traffic issues as there is a dedicated link between two devices. • It is secure because there is a point to point link thus unauthorized access is not possible.
- 65. Limitations • Most expensive because it requires more cables than other topologies. • Difficult to implement. • Difficult to add new computer.
- 67. Communication via telephone networks • Telephone network is commonly used for data communications because it exists all over the world. • Following are the communication lines provided via telephone networks: • Dial-up line • Digital Subscriber Line(DSL) • Integrated Services Digital Network(ISDN) lines • Code Division Multiple Access (CDMA)
- 68. DIAL-UP line • Dial-up line provide standard telephone network • Maximum speed of dial line is 56 kilobits per second which is very slow. • It is being replaced by faster DSL connection for internet.
- 69. Digital Subscriber Line (DSL)
- 70. DSL • It provides high speed internet connection. • It is called broadband because it has broad range of frequencies for transmitting digital data. • Its speed is 256KBPS • DSL service is “always on” and lets you surf the web while using your landline phone.
- 71. Integrated Service Digital Network (ISDN) line
- 72. Integrated Service Digital Network (ISDN) line • It provide a maximum speed of 128kbps • Faster then dial up line and slower than DSL lines • It can transmit both voice and data at the same time. • Sometimes DSL in villages can only reach speeds of 1 to 2 Mbps, so ISDN access is preferable.
- 74. Code Division Multiple Access (CDMA) • It is a wireless cellular communication technology • Include short messaging ,voice, data and video transmission • Provide speed of several Mbps.
- 75. Code Division Multiple Access (CDMA
- 76. Code Division Multiple Access (CDMA