1. ITT 413 Basics of Data Communication

2. Overview  Assessment Plan Coursework – 40% Final Exam – 60%  Course Content

3. What is Computer Communication? Introduction  Computer?  Communication?

4. Elements of Computer communication  Sender  Receiver  Message  Medium  Protocols

6.  Sender: The sender is the device that sends the message (data). It can be a computer, workstation, mobile handset or a video camera  Receiver:  Receiver: The receiver is the device that receives the message. It can be a computer, workstation, mobile handset or television  Message:  Message: The message is the information (data) to be communicated. It can be a text message, number, picture, sound, video or a combination of these  Medium:  Medium: The transmission medium is the physical path by which a message travels from sender to receiver. It could be a cable (twisted pair), fiber optic or air  Protocol: what is communicatehow it is communicated when it is communicate  Protocol: A protocol is a set of rules that govern computer communication. It present an agreement between communicating devices. A protocol define what is communicate, how it is communicated and when it is communicate

7. SyntaxSemanticTiming Key elements of a protocol are: Syntax, Semantic and Timing Syntax: Syntax: Syntax refer to the structure or format of the data, meaning the order in which they are presented Semantics: Semantics: Semantics refers to the meaning of the section of bits. How is a particular pattern to be interpreted? and what action is to be taken based on that interpretation? Timing: Timing: Timing refers to two characteristics: when data should be sent and how fast they should be sent

8. Transmission Modes  Simplex  Half-Duplex  Full-Duplex direction of a signal transmission modetransmission mode direction of a signal The direction of a signal between two devices is defined by a transmission mode. Or The transmission mode defines the direction of a signal between two devices

9. Simplex remote is an example In the simplex mode the communication is unidirectional. Only one can send data and other can receive. No any other possibility is available. A remote is an example of simplex mode.

10. For example, in TV and radio broadcasting, information flows only from the transmitter site to multiple receivers. Commercial radio and television broadcast (not two-way radio such as walkie-talkies) Garage door openers Baby monitors Wireless microphones Radio controlled models Public address systems Surveillance cameras Pagers Communication between a mouse and a computer Internet multicast Radio navigation beacons and radiolocation services such as GPS Telemetry Printers Example of Simplex Communication

11. Half-Duplex Transmission Half Duplex Mode: FAX (it can sends or receives letter but not in same time) Walkie- talkie is an example of half duplex transmission Half Duplex Mode: In the Half-duplex (sometimes it is called an alternating connection or semi-duplex) mode, the data can be transmitted from one direction to the other. The terminals have ability to either receives or sends out the data. However, sending and receiving can not be done at same time. For example; FAX (it can sends or receives letter but not in same time) and Walkie- talkie is an example of half duplex transmission

13. Full-Duplex Transmission MSN-hotmail, Yahoo messanger, google talk, facebook chatt-room and Skype telephone Full Duplex Mode: In full duplex mode both devices can send and receive data at the same time. It has two way traffic at the same time or its like a two lane bridge on a two-lane highway. Online communication such as MSN-hotmail, Yahoo messanger, google talk, facebook chatt-room and Skype telephone are the one of the examples of software, which are in full-duplex and also the telephone network (example landline and mobile) is an example of full duplex mode.

17. Categories of Networks A network is a set of devices (nodes) connected by media links. A node can be a computer, printer, or any other devices capable of sending and /or receiving data generated by another node in the network

18. LAN LAN LAN is usually privately owned and interconnect devices in a single office, building, or campus (see the figure below)

19. MAN For example, UDSM with many campuses mliman, kunduchi, and DCE. MAN is designed to extend over an entire city. It may be single network such as cable television network, or it may be a means of connecting a number of LANs into a large network so that resources can be shared. For example, UDSM with many campuses mliman, kunduchi, and DCE.

20. WAN For example the internet WAN provides a long-distance transmission of data, voice, image and video information over large geographical area that may comprises a country, a continent, or even the whole world. For example the internet

21. LAN COMPONENTS hardware and software.  LAN is the combination of hardware and software.  Hardware is the part of the network that is tangible whereas Software is the collection of programs that allows the use of network

22.  Stations  Transmission media  Connecting Devices Hardware:

23. Software: Network operating system (NOS) and application programs Software run on a LAN can be divided into two larger groups: Network operating system (NOS) and application programs Network Operating system (NOS) Novell NetWare, Microsoft Windows NT, Microsoft Windows 2000, Microsoft Windows XP, Sun Solaris, Linux. Network Operating system (NOS) : is a program that allows logical connection of the stations and devices to the network. It allows users to communicate and share resource. Some examples of network operating systems include Novell NetWare, Microsoft Windows NT, Microsoft Windows 2000, Microsoft Windows XP, Sun Solaris, Linux.

24. Application programs allow users to solve special problems In this case applications is either the program you are using or the data you are working with or both reside on a network. Network applications use a client-server architecture, where the client and server are two computers connected to the network. The server is programmed to provide some service to the client. The client is typically a desktop, laptop or portable device like an smart phone. The server can be any of these, but is typically a computer in a data center. Examples of network applications are: E-mail, The Web, Instant Messaging, P2P file sharing, File Transfer between two accounts on two computers (FTP) Multi-user networked games, Streaming stored video clips, Internet Phone, Real time video conferencing Application Programs

26. Client/Server Model with Dedicated Servers

27. Client/Server Model with a General Server

28. LAN Applications Common applications of LAN are office networks and industry network Office Networks hardware, software and data. Office Networks: LANs are used for sharing resources such as hardware, software and data. Hardware – example printer Software – example accounting package (program) Data – example bank customer’s information Industry Network Industry Network : This is suitable for automated manufacturing and production. For example, a LAN can be used in the automobile industry such as TOYOTA to coordinate different activities such as controlling robots, material handling, or warehouse inventory