Computer Networks (EC-321) Credits : 3(2,1)

1. Computer Networks (EC-321)Credits: 3(2,1)

2. Outline • Instructor/Material/Exam • Objectives/Goals • Course Contents • Course Outcome • Introduction

3. Instructor/Material/Exam (1) • Who am I Umar Shahzad • Education: MS (Computer Science and Networking) • Experience: Post graduate (1.5 years in Telecommunication Industry) • Email: engr.umarshahzad@yahoo.com Availability after Class times: • Contact after the class • Email

4. Instructor/Material/Exam (2) Text Book: • Computer Networks – By Andrew S. Tanenbaum, Latest Edition. References: • Computer Networks: a top down approach by Keith Ross and J.Kurose, 3rd Ed • Data and Computer Communication by W.Stalling, 7th Ed • Paper for review

5. Instructor/Material/Exam (3) Exam Policy: Written test • Closed books • Open questions, multiple-choice questions and problems Note: • There can be a slight change in the exam pattern (will be informed)

6. Objectives/Goals • Introduce to fundamental techniques/principles of CN. • Ability to design different networks and analyze the performance by using simulating or monitoring tool. • Develop understanding of the communication protocols used in internet. • Ability to design and analyse MAC, Routing and Transport layer protocols for different networks. • Network programming skills : socket to implement various applications based on client/server paradigm or peer-to-peer communication. • Introduce to emerging networking technologies 3G/4G

7. Course Contents • Introduction • Uses of Computer Networks • Network Hardware and Software • Reference Models • Example Networks • Network Standardization • The Physical Layer • Basis for Conventional Data Communication • Transmission Media • Wireless Transmission • Communication Satellites • Telephone System, Mobile Telephone System • Cable Television

8. Course Contents (cont.) • Data Link Layer • Design Issues • Error Detection and Correction • Elementary Data Link Protocols • Sliding Window Protocols • Protocol Specification and Verification • Example Data Link Protocols • MAC sub-layer • Channel Allocation Problem • Multiple Access Protocols • Bridges • High-Speed LANs

9. Course Contents (cont.) • Wireless Systems, Technologies, Protocols • Evolution and Standards • Intro to radio propagation • Interference and PHY layer issue • Intro to MAC layer design and protocols • Network layer • Design Issues • Routing Algos • Congestion Control Algos • Internetworking • Network Layer in Internet

10. Course Contents (cont.) • Transport Layer • Transport Service • Elements of Transport Protocols • TCP and UDP • A simple Transport Protocol • Performance Issues • The Application Layer • DNS • Electronic mail • WWW • Multimedia

11. Course Outcome • Adequate knowledge of fundamental techniques of computer networks particularly internet. • They will be able to design protocols and implement.

12. Introduction • Basics and Background • Uses of Computer Networks • Network Hardware and Software • Reference Models • Example Networks • Network Standardization

13. Basics and Background • What’s a network? • Merriam-Webster Dictionary: • “A fabric or structure of cords or wires that cross at regular intervals…” • “A system of computers, terminals and databases connected by communication lines” • “A computer network is defined as the interconnection of 2 or more independent computers.” [Ramteke,”Networks”, pg. 24].

14. Basics and Background (cont.) • Why network? • Before networks: • One large, expensive computer (mainframe) in “computer center” used for all processing in businesses, universities, etc. • Smaller, cheaper computers… • Personal computers or workstations on desktops. • Interconnecting many smaller computers is advantageous! Why? • Large number of separate but interconnected computers do the job.

15. Basics and Background (cont.) • Why network? • Computers everywhere. • Also means ubiquitous communication. • Users connected anywhere/anytime. • PC, laptop, cell phone. • Networking computers together is critical! • Provide access to local and remote resources. • Collection of interconnected end systems: • Computing devices (mainframes, workstations, PCs) • Peripherals (printers, scanners, terminals).

16. Basics and Background (cont.) • Why network? • Resource sharing! • Hardware: printers, disks, terminals, etc. • Software: text processors, compilers, etc. • Data. • Robustness. • Fault tolerance through redundancy. • Load balancing. • Processing and data can be distributed over the network. • Location independence. • Users can access their files, etc. from anywhere in the network

17. Introduction • Basics and Background • Uses of Computer Networks • Network Hardware and Software • Reference Models • Example Networks • Network Standardization

18. Uses of Computer Networks • Business Applications • Home Applications • Mobile Users • Social Issues

19. Business Applications (1) • Resource sharing • All programs, equipment, and especially data available to anyone on the network without regard to the physical location of the resource or the user e.g printer, information sharing (inventory, customer records, product information etc.) • Scattered offices and plants around the globe can be connected e.g VPNs (individual scattered networks ------ one extended network)

20. Business Applications (2) • Power-full computer store company’s data. • A network with two clients and one server.

21. Business Applications (3) • The client-server model involves requests and replies. • IP telephony or Voice over IP (VoIP) • A person at home accesses a page on the World Wide Web, the same model is employed, with the remote Web server being the server and the user’s personal computer being the client. • Desktop sharing lets remote workers see and interact with a graphical computer screen. • e-commerce e.gAirlines • Etc…..

22. Uses of Computer Networks • Business Applications • Home Applications • Mobile Users • Social Issues

23. Home Applications • Access to remote information • surfing the World Wide Web for information or just for fun e.g online newspaper • Online digital library e.g ACM, IEEE, ebooks • Peer-to-Peer • Every person can, in principle, communicate with one or more other people; there is no fixed division into clients and servers e.gBitTorrent. • do not have any central database of content.

24. Home Applications

25. Home Applications • Person-to-person communication • above applications involve interactions between a person and a remote database full of information • Email, Instant messaging, Twitter • Between person-to-person communications and accessing information are social network applications e.g Facebook • Interactive entertainment • MP3 songs, DVD-quality movies and IPTV etc

26. Home Applications • Electronic commerce • Home shopping • Access to financial institutions e.g online bills payment, manage their bank accounts, and handle their investments electronically. • Some forms of e-commerce.

27. Home Applications • ubiquitous computing • Homes equipped with sensors like security systems that include door and window sensors, smoke detectors call to fire department instead of making noise • electricity, gas and water meters could also report usage over the network • Etc…..

28. Uses of Computer Networks • Business Applications • Home Applications • Mobile Users • Social Issues

29. Mobile Users • People on the go often want to use their mobile devices to read and send email, tweet, watch movies, download music, play games, or simply to surf the Web for information • Wireless hotspots, cellular companies provide internet • Smart phones, such as the popular iPhone, combine aspects of mobile phones and mobile computers • m-commerce (mobile-commerce) (Senn, 2000). Short text messages from the mobile are used to authorize payments for food in vending machines, movie tickets, and other small items instead of cash and credit cards • Wearable computers are another promising application. Smart watches with radios.

30. Mobile Users • distinction between fixed wireless and mobile wireless networks

31. Uses of Computer Networks • Business Applications • Home Applications • Mobile Users • Social Issues

32. Social Issues • Along with the good comes the bad, this new-found freedom brings with it many unsolved social, political, and ethical issues. • Social networks, message boards, content sharing sites, and a host of other applications allow people to share their views with like-minded individuals. • As long as the subjects are restricted to technical topics or hobbies like gardening, not too many problems will arise. • The trouble comes with topics that people actually care about, like politics, religion etc.

33. Introduction • Basics and Background • Uses of Computer Networks • Network Hardware and Software • Reference Models • Example Networks • Network Standardization

34. Network Hardware (1) • Two dimensions stand out as important in computer networks • transmission technology • Scale • Types of transmission technology • Broadcast links • Point-to-point links

35. Network Hardware (2) • Point-to-point links • connect individual pairs of machines. • To go from the source to the destination on a network made up of point-to-point links, short messages, called packets in certain contexts, may have to first visit one or more intermediate machines. • Finding good routeis important in point-to-point networks. • One sender and exactly one receiver is sometimes called unicasting.

36. Network Hardware (3) • Broadcast links • the communication channel is shared by all the machines on the network; packets sent by any machine are received by all the others. • intended recipient • all destinations ---broadcasting

37. Network Hardware (4) • Scale • Distance is important as a classification metric because different technologies are used at different scales.

38. Network Hardware (5) • Personal Area Networks • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Internetworks

39. PAN • PANs (Personal Area Networks) let devices communicate over the range of a person e.g computer connect with its peripherals • Cables • Bluetooth (master, slave paradigm) • master tells the slaves what addresses to use, when they can broadcast, how long they can transmit, what frequencies they can use, and so on • PANs can also be built with other technologies that communicate over short ranges, such as RFID on smartcards and library books

40. Network Hardware (5) • Personal Area Networks • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Internetworks

41. LAN (1) • LAN (Local Area Network) is a privately owned network that operates within and nearby a single building like a home, office or factory. • widely used to connect personal computers and consumer electronics to let them share resources (e.g., printers) and exchange information. • When LANs are used by companies, they are called enterprise networks.

42. LAN (2) • topology of many wired LANs is built from point-to-point links • Ethernet (802.3), is the most common type of wired LAN

43. LAN (3) • Divide one large physical LAN into two smaller logical LANs is possible • VLAN • Two broadcast networks • (a) Bus • (b) Ring

44. LAN (4) Token Ring (Ring Topology)

45. LAN (5) • Wireless and wired broadcast networks, depending on channel allocation, can be divided into • static (time in discrete intervals, round robin) • dynamic designs (centralized (e.g base station) and decentralized (e.gchoas like situation, CSMA/CD)) • Modern Home LAN • Sensors e.g fire sensor • Meter reading, clock (DLS) • IP of Things etc…

46. Network Hardware (5) • Personal Area Networks • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Internetworks

47. MAN • A MAN (Metropolitan Area Network) covers a city • (WiMAX(802.16))Wireless MAN) • A metropolitan area network based on cable TV.

48. Network Hardware (5) • Personal Area Networks • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Internetworks

49. WAN (1) • A WAN (Long Haul) spans a large geographical area, often a country or continent. Hosts

50. WAN (2) • A WAN (Long Haul) spans a large geographical area, often a country or continent. (Switching Element) Transmission Lines Hosts