Information and Communication Technology Fundamentals

1. Information and Communication Technology Fundamentals Credits Hours: 2+1 Instructor: Ayesha Bint Saleem

2. NETWORKS - I

3. Presentation Credits • “Introduction to Computers”, Peter Norton • “Computer Networks”, Tanenbaum • Dr Altaf Khan, Virtual University

4. Networks is a set of technologies – including hardware, software and media – that can be used to connect computers together, enabling them to communicate, exchange information and share resources in real time

5. Example • Web Browsing application • Software • Protocols involved • Software • NIC / Modem • Hardware • Telephone line / Co-axial cable / Air interface • Media

6. Why do you want to have Networks?

7. Uses of Networks • Sharing Resources • 1 printer , many people wanting to print • Access to same data and programs • Servers • Personal Communication • Email • Audio/Video/Data Conferencing

8. Uses of Networks • Access to remote resources • File downloads • Data Backups • Shared storage device • Regular data backup • Greater performance • Distributed computing

9. Types of Computer Networksaccording to the distance between nodes • LAN: Local Area Network • WAN: Wide Area Network

10. LAN • A network of computers located in the same building or a handful of nearby buildings • Examples: • Computer network at SEECS • Computer network of a University campus

11. WAN • A network in which computers are separated by great distances, typically across cities or even continents • May consist of several interconnected LANs • Example: • The network connecting the ATM of a bank located in various cities • A network connecting the local and oversea offices of a SW house • Internet

12. Hybrid Networks • Metropolitan Area Networks • Campus Area Networks • Home Area Networks • Personal Area Networks

13. Classification (Geographical Scope) • Wide Area Networks • Metropolitan Area Networks • Campus Area Networks • Local Area Networks • Home Area Networks • Personal Area Networks Decreasing Scope

14. Software part of a Network • Application • Email • Browsing • Conferencing • Chatting (text/voice) • File Transfer • Audio/Video Streaming

15. Software part of a Network • Protocols • Language that a computer uses to achieve data communication • Set of Rules

16. Packet • The smallest unit of data transmitted over a computer network • A message to be transferred over the network is broken up into small packets by the sending computer

17. Packet • Each packet consists of • Header part • Contains control info to assist in routing of the packet • Source address • Destination address • Payload part • Contains actual data • Error control part Header Payload Error Control Packet

18. Packet • All packets travel independently • When all packets are received by the destination computer, it reassembles them to form the original message

19. Hardware part of a network

20. Modem • Plain Old Telephone System (POTS) • Standard phone line • Two-way voice communication • Uses analog transmission techniques • Data communication is slow

21. Modem • Modem • Modulator/DEModulator • Computer sends data in digital form • Modem provides a hardware interface between computer and telephone lines • Transmission speed upto 56Kbps • V.92 is the current modem standard • Several modem types • Internal • External • Voice • Fax

22. ISDN • Integrated Services Digital Network • Basic rate uses three channels • Basic Rate Interface (BRI) • Two data channels each support 64 Kbps • Control channel 16kbps • Primary rate uses 24/32 channels • Primary Rate Interface (PRI) • U.S standard: 23 data channels each supporting 64 kbps, 1 control channel at 64 kbps • Europe standard: 30 data channels each supporting 64 kbps, 2 control channel at 64 kbps • ISDN adapter required at computer

23. ISDN

24. DSL • Digital Subscriber Line (DSL) Modem • Newer technology to provide better data rates over the telephone lines • Several versions exist • Different transfer rates for different version • Asymmetrical DSL (ADSL) • Upload speed slower than download speed • Symmetrical DSL (SDSL) • 100 Kbps to 30 Mbps

25. LAN Card • Network Interface Card (NIC) • LAN card • Digital Interface + Protocol • Provides higher data rates

26. ATM • ATM • Asynchronous Transfer Mode • Efficient transfer of video and sound • Real Time traffic • Requires a special NIC and hardware

27. Wireless LAN Card • Wireless NIC • Transmission over air is not digital • Provides Interface + Protocol • IEEE 802.11 • Also called Wi-Fi • Institute of Electronic and Electrical Engineers • Several versions • 802.11b connects up to 11Mbps • 802.11g connects up to 56Mbps • 802.11n connects up to 600Mbps

28. WLAN Card

29. Where is all this hardware located?

30. Now that we have some software and hardware on each computer.. How can we connect these computers?

31. Network Topologies • Topology • Logical layout of wires and equipment • Choice affects • Network performance • Network size • Network collision detection • Several different types

32. Point-to-Point (P2P) Computer A Computer B

33. P2P • Inexpensive • Limited connectivity • Quite often used for connecting two LANs to form a WAN

34. Network Topologies • Bus topology • Also called linear bus • One wire connects all nodes • Terminator ends the wires • Advantages • Easy to setup • Small amount of wire • Disadvantages • Slow • Easy to crash

35. Network Topologies • Star topology • All nodes connect to a single device e.g. hub • Packets sent to hub • Hub sends packet to destination • Advantages • Easy to setup • One cable can not crash network • Disadvantages • One hub crashing downs entire network • Uses lots of cable • Most common topology

36. Network Topologies

37. Network Topology • Ring topology • Nodes connected in a circle • Tokens used to transmit data • Nodes must wait for token to send • Advantages • Time to send data is known • No data collisions • Disadvantages • Slow • Lots of cable

38. Network Topology • Mesh topology • All computers connected together • Internet is a mesh network • Advantage • Data will always be delivered • Disadvantages • Lots of cable • Hard to setup

39. Network Topology

40. Linking Hardware Computer E Computer A Computer D Linking Hardware Computer B Computer C

41. Types of Linking Hardware • Hubs • Bridges • Switches • Routers • Gateways

42. Hub • A device that is used to connect several computers to form a network • A hub has several ports. The number generally is 8, 12, 16, 24, 32, or 48 • Most dumb among all linking devices

43. Hub • Each computer in a network is connected to one of those ports through a cable • A computer wanting to send a message to one of the others in the network sends a message to the hub, which, in turn, broadcasts the message to all others connected to it

44. Bridge • Used to form a connection between two separate, but similar networks • In a way, it creates an extended LAN by passing information between two or more LANs • Packets sent to remote LAN cross • Other packets do not cross

45. Switch • Has multiple ports • Learns which machine is connected to which port • Only intended node receives transmission • Reduces broadcast traffic

46. Router • Connects two or more LANs together • Packets sent to remote LAN cross • Network is segmented by IP address • Connect internal networks to the Internet • Need configured before installation

47. Router • Examines the destination info in each arriving packet • Routes it through the most efficient path available • Either delivers the packet to the destination computer across a local network • OR forwards the packet to another router that is closer to the final destination

48. Gateway • A special-purpose computer that connects and translates between networks that use different communications protocols • LAN’s may use a gateway (or router) to connect to the Internet

49. How to Connect? Network Media

50. Network Media • Links that connect nodes • Choice impacts • Speed • Security • Size