COTN1220_01_Introduction.pdf

COTN 1220 – Data Communication Introduction DATA COMMUNICATION Data – information presented in whatever form is agreed upon by the parties creating and using the data. Telecommunication – communication at a distance. Data communications – the exchange of data between two devices via some form...

COTN 1220 – Data Communication Introduction DATA COMMUNICATION Data – information presented in whatever form is agreed upon by the parties creating and using the data. Telecommunication – communication at a distance. Data communications – the exchange of data between two devices via some form of transmission medium such as a wire cable. COMPONENTS OF DATA COMMUNICATION 1. Message – the information (data) to be communicated. 2. Sender– device that sends the data message. (computer, workstation, telephone, video camera, etc.) 3. Receiver– device that receives the message. 4. Transmission medium – physical path by which a message travels from sender to receiver. (STP, coaxial, fiber, etc.) 5. Protocol – rules that govern data communications. DATA REPRESENTATION Text – represented by bit patterns (sequence of bits). Usually represented by the American Standard Code for Information Interchange (ASCII) code. Numbers – bit pattern converted directly to binary numbers. Images – bit pattern composed of a matrix of pixels. Audio Video DATA FLOW a. Simplex – communication is unidirectional. One transmit and the other only receives. Example: Monitor, keyboard b. Half-Duplex – both can transmit an receive, but not at the same time. Example: CB Radio c. Full-Duplex – both can transmit and receive simultaneously. Example: Telephone NETWORKS Network– set of devices (often referred to as nodes) connected by communication links. Node – a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. Distributed processing – tasks are divided among multiple computers. Used by most networks. Network Criteria Performance – throughput & delay. Reliability – frequency of failure, recovery from failure, robustness. Security –protecting the data. PHYSICAL STRUCTURES Networks can be categorized physically by: Type of connection Point-to-Point Multipoint Physical Topology Mesh Star Topology Bus Topology Ring Topology Hybrid Topology Let's take a look at each of them in detail… TYPE OF CONNECTION a. Point-to-Point –dedicated link between two devices. b. Multipoint – multiple devices share a single link. TOPOLOGY Physical topology – the way in which a network is laid out physically. 2+ devices = link, 2+ links = topology Not the same as a logical topology!!! TOPOLOGY (cont.) Mesh topology – every device connected to every other device. (Point-to-Point) 𝑛 𝑛−1 Number of links = , where n is the 2 number of nodes. Number of I/O ports? 1 2 6 3 7 8 4 9 10 5 TOPOLOGY (cont.) Mesh topology Advantages Dedicated links between nodes Robust Privacy Easy fault identification and isolation Disadvantages Amount cabling Cost TOPOLOGY (cont.) Star topology – every device connected to a central node, usually a hub. (Point-to-Point) Advantages Less expensive than the mesh topology. Robustness Easy fault identification and isolation Disadvantage Central point dependency Number of links = n TOPOLOGY (cont.) Bus topology – all devices connected to a backbone. (Multipoint) Advantages Ease of installation Disadvantage Difficult fault identification and isolation Signal degradation Number of links = n droplines, 1 backbone TOPOLOGY (cont.) Ring topology – each device connected to the two device next to it. (Point-to-Point) Advantages Easy fault identification and isolation Easy reconfiguration Disadvantage Unidirectional traffic Number of links = n-1 TOPOLOGY (cont.) Hybrid topology – Mixture of any of the four basic topology. CATEGORIES OF NETWORKS Personal Area Network (PAN) A wireless network that connects information technology devices close to one person. With a PAN, you can connect a laptop, digital camera, and portable printer without cables. A PAN could also be used to enable data captured by sensors placed on your body to be transmitted to your smartphone CATEGORIES OF NETWORKS Local Area Network A network that connects computer systems and devices within a small area, such as an office, home, or several floors in a building Allow resources to be shared. Most common topologies are bus, ring, and star. CATEGORIES OF NETWORKS Campus Area Network (CAN) Provides wireless access to the Internet or LAN for the users located in two or more buildings on the limited geographical area Or in the open space surrounding these buildings. Usually set in campus of a university or college Can also be used for enterprises, office buildings, military bases, industrial complexes, public places like supermarkets, entertainment centers, etc. Can be temporary during special events. CATEGORIES OF NETWORKS (cont.) Metropolitan Area Networks (MAN) Connects users and their devices in an area that spans a campus or city Between a LAN and a WAN in size. Designed for customers who need a high-speed connectivity Internetwork - two or more networks connected. CATEGORIES OF NETWORKS (cont.) Wide Area Network (WAN) Connects large geographic regions WANs consist of: Computer equipment owned by the user Data communications equipment and telecommunications links provided by various carriers and service providers Communications may involve transborder data flow CATEGORIES OF NETWORKS (cont.) Wide Area Network (cont.) b. Point-to-Point WAN– connects a home computer or a small LAN to an Internet service provider (lSP). PUTTING IT ALL TOGETHER A heterogeneous network made of four WANs and two LANs THE INTERNET (cont.) PROTOCOLS VS. STANDARD Protocol - is a set of rules that govern data communications. What, How, When Standard – guidelines to ensure interconnectivity Standards Organizations International Organization for Standardization (ISO) American National Standards Institute (ANSI) Institute of Electrical and Electronics Engineers (IEEE) THE INTERNET internet two or more networks that can communicate with each other. Internet a collaboration of more than hundreds of thousands of interconnected networks. 1969 – ARPANET Nodes – UCLA, UCSB, SRI, Utah. CHARACTERISTICS OF DATA COMMUNICATION 1. Delivery– deliver data to the correct location. 2. Accuracy– must deliver the data accurately, must not have been altered in transmission. 3. Timeliness– must deliver data in a timely manner. Late data is useless! 4. Jitter– variation in the packet arrival time. Uneven delay in the delivery of audio or video packets.