CPSC441

1. CPSC441 Computer Communication

2. What this Course is About? • Provide an introduction to modern telecommunications and computer networks, including information about : • the physical characteristics of current transmission media • layered protocol hierarchies commonly used for the organization of modern networks • standards and protocols for several of these layers.

3. Topics • INTRODUCTION • PHYSICAL LAYER • DATA LINK LAYER • NETWORK LAYER • TRANSPORT LAYER • APPLICATION LAYER • TCP/IP SECURITY

4. Topics • INTRODUCTION • HISTORY • TYPES OF NETWORKS: LAN, WAN • TYPES OF NETWORKS: Client - Server, Peer to Peer • THEORETICAL NETWORK: OSI model, TCP/IP model • EXAMPLES OF NETWORKS, SERVICES • PHYSICAL LAYER • DATA LINK LAYER • NETWORK LAYER • TRANSPORT LAYER • APPLICATION LAYER • TCP/IP SECURITY

5. Topics • INTRODUCTION • PHYSICAL LAYER • SOME PHYSICS • TRANSMISSION MEDIA, MODULATION • TELEPHONE SYSTEM, MODEMS • BASEBAND, BROADBAND TRANSMISSION • ATM TRANSMISSION • DATA LINK LAYER • NETWORK LAYER • TRANSPORT LAYER • APPLICATION LAYER • TCP/IP SECURITY

6. Topics • INTRODUCTION • PHYSICAL LAYER • DATA LINK LAYER • FRAMES, FRAME MANAGEMENT • ERROR CHECKING • DATA LINK PROTOCOLS • EXAMPLES: ETHERNET, TOKEN RING, others • NETWORK LAYER • TRANSPORT LAYER • APPLICATION LAYER • TCP/IP SECURITY

7. Topics • INTRODUCTION • PHYSICAL LAYER • DATA LINK LAYER • NETWORK LAYER • ROUTING, ROUTING PROTOCOLS • IP ADDRESSING, SUBNETS, NETMASK • TRANSPORT LAYER • APPLICATION LAYER • TCP/IP SECURITY

8. Topics • INTRODUCTION • PHYSICAL LAYER • DATA LINK LAYER • NETWORK LAYER • TRANSPORT LAYER • TCP, UDP protocols • SOCKET PROGRAMMING • APPLICATION LAYER • TCP/IP SECURITY

9. Topics • INTRODUCTION • PHYSICAL LAYER • DATA LINK LAYER • NETWORK LAYER • TRANSPORT LAYER • APPLICATION LAYER • Domain Name Service (DNS) • BASIC INTERNET SERVICES • TCP/IP SECURITY

10. Topics • INTRODUCTION • PHYSICAL LAYER • DATA LINK LAYER • NETWORK LAYER • TRANSPORT LAYER • APPLICATION LAYER • TCP/IP SECURITY • INTRO TO CRYPTOGRAPHY • Secure Socket Layer (SSL) • FIREWALLS

11. Quotes • Computers in the future may weigh no more than 1.5 tons • “I think there is a world market for maybe five computers.” Thomas Watson Chairman of IBM 1943 • “There is no reason anyone would want a computer in their home” Ken Olson president DEC 1977 • “640K ought to be enough for anybody” Bill Gates 1981

12. History of Data Communications • Communications industry was already established at the beginning of the computer era. • First type of data communication was terminals attached to mainframes via modems and telephone lines.

13. History of Data Communications • Development of Semi-Automatic Business Research Environment (SABRE) • Development of Packet Distribution Network (PDN), allowed Advanced Research Projects Agency (ARPA) to develop ARPANET.

14. History of Data Communications • Development of other Proprietary Computer Networks (works on one manufacturers equipment) • Systems Network Architecture (SNA) developed by IBM • Decnet Developed by Digital • Telnet developed by General Telephone and Electronics (GTE)

15. Historical Events • 1948 first commercial computer installed UNIVAC I • 1958 first U.S. communication satellite • 1964 SABRE airline reservation system packet switching network (purposed by RAND) • 1969 ARPANET first packet switching network begins operation

16. Historical Events • 1971 first computer chip • 4 bit, 2,300 transistors • 1972 Ethernet specifications formulated • 1974 IBM introduces SNA • 1975 Altair 8800 first commercial microcomputer sold as kit

17. Historical Events • 1975 Paul Alan / Bill Gates wrote a BASIC language interpreter for the Altair, they formed Microsoft • 1976 Woznaik and Jobs built Apple I and formed Apple Computer Company • 1979 VisiCalc first commercial spread sheet introduced

18. Historical Events • 1981 IBM introduced IBM PC one floppy • 1983 TCP/IP becomes the official protocol on ARPANET • 1984 Apple introduced GUI with Apple Macintosh • 1986 PC Convertible (first laptop (luggable))

19. Historical Events • 1988 OS/2 shipped by IBM first multitasking operating system for PC 1989 Intel releases 486 • 1989 Microsoft releases Windows 3.0 1991 • 1989 NSF replaces ARPANET as internet backbone • 1991 WWW invented by CERN physicist Tim Berners-Lee

20. Historical Events • 1992 Mosaic release first GUI web browser • 1995 Netscape goes from startup to $2.9 billion in one year • 2000 .com melt down

21. Data Communications Data Communications Terminal to Computer Computer to Computer Local Area Networks Wide Area Networks Peer to Peer Client Server

22. PC as an Information tool • Local Area Network (LAN) • number of computers connected together • usually a small geographical area • office, floor, classroom • share resources (software, hardware)

23. PC as an Information Tool • Wide Area Network (WAN) • connection of LANs • connected by wire, microwave, satellite

24. Resource Sharing • Sharing of Information • Types • Mission critical data • Frequently used data (form letters) • Policy / procedure manuals • Who needs what access • update • read only

25. Information Sharing • What information is vital to your organization • What information do you need to keep consistent, or restricted, or in one place for everyone to access • Consider how a network (centralized control) would help

26. Hardware Sharing • Allows sharing of devices such as: • Printers • Fax modems • Scanners • Disk drives • CD ROM's • Tape Backup units • Plotters

27. Software Sharing • Software need not be installed on every computer • One install, one central location for updates • Consistent configuration • Grant or deny access to a program

28. Software Sharing • License considerations • single user • license per user • site license

29. Backup • Backup of central server or disk • Hard to backup a number of stand alone computers • Usually backup of workstation is responsibility of the user

30. Computer Roles in a Network • Clients • use network resources • provide no resources to the network • run their own operating system • Servers • provide resources to the network • Peers • use and provide services

31. Operating systems • Server • Novel NetWare • Windows NT • Client • Windows 2000 • DOS • OS/2 • Peer • Windows 2000

32. Categories of Networks • Client / Server • contains clients and supporting servers • may be dedicated or non dedicated • server centric • network centric

33. Categories of Networks • Peer to Peer • network of computers sharing resources with no dedicated server

34. Server Based Networks • Advantages • Strong central security • Central file storage (backup, data organization) • Share hardware and software • Optimize dedicated servers for special purpose • Less intrusive security (network centric) • manages shared resources • manages users

35. Server Based Networks • Disadvantages • Expensive hardware • Expensive software • Dedicated network administrator

36. Peer to Peer • Advantages • no extra hardware or software • easy setup • no network administrator • users control resource sharing • no reliance on other computers for their operation • lower cost for small networks

37. Peer to Peer • Disadvantages • additional load on computers because of resource sharing • smaller networks • lack of central organization, harder to find data • no central point of storage (backup) • user administer their network • weak security • no central management

38. Peer Security /Server Security • Peer to Peer • less secure than client server • security is controlled by access to a share directory (password) • each resource requires a separate password • cannot distinguish between users • Client / Server • network logins • permissions granted to users for files / resources

39. Home Network Applications (2) • In peer-to-peer system there are no fixed clients and servers.

40. Selecting the Network type • Cost • Expertise • Security issues • Number of work stations • Types of applications

41. Types of servers • Servers can designed for a specialized purpose • file servers • print servers • Application servers • Message servers • database servers • Web servers • One server (hardware / software) may perform one or more functions

42. File Servers • Offer services that allow users to share files • Typical operating systems • Novel NetWare, Windows NT • Services include • file transfer • file storage and data migration • file update synchronization • file archiving

43. File ServersFile Transfer • The ability to transfer files from one computer to another • Need for security (who has what access to which files) • Historical done by sneaker net

44. File ServersFile Storage and Data Migration • Vast amounts of data is stored (exabytes) • Must be able to efficiently manage the storage of this data • Categories of file storage • Online storage • Offline storage

45. File StorageOnline • Online storage consists mostly of hard drives • Online information is immediately available

46. File StorageOffline • Offline storage include media such as tape, optical disk • High capacity, low price • Not immediately available • Need for operator intervention • Best for rarely used data (backup)

47. File ServerFile Archiving • Process of backing up files on offline devices • Most systems backup file server data • Some backup client workstations • Usually the backup of the client (workstation) is the users responsibility

48. Print Servers • Manages and controls printing on the network • allows users to share printers • place printers where convenient • better workstation performance by using high speed data transfer, print queues and spooling • ability to send and receive faxes directly from the work station

49. Application Servers • Allow sharing of extra computing of expensive software applications that reside on a shared computer

50. Message Servers • Message services coordinate interactions between users, documents and applications • Interactions may be graphics, audio, video, etc. • Types of message services • Electronic mail • Workgroup applications • Object oriented • Directory services