lec-1.pptx.pdf

CS1210|SE1210|IT 1211 Data Communication and Networks Lecture 1 2024/05/03 Bachelor of Information Technology Department of Computing...

CS1210|SE1210|IT 1211 Data Communication and Networks Lecture 1 2024/05/03 Bachelor of Information Technology Department of Computing Faculty of Computing and Technology Saegis Campus Nugegoda Udaya Perera 1 Recommended Reading: Oliver, C.: Fundamentals of Data Communication Networks. 1 ed. USA (2017). White, c.: Data Communications and Computer Networks: A Business User's Approach. 8 ed. Cengage Learning, (2015). 2 What is Network ???? A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams. 3 What is data communication??? Data communication is the process of transferring data from one place to another or between two locations. It allows electronic and digital data to move between two networks, no matter where the two are located geographically, what the data contains, or what format they are in. 4 The type of data transmission. Simplex data transmission: Data is sent from sender to receiver Half-duplex data transmission: Data can transmit both ways, but not simultaneously Full-duplex data transmission: Data can transmit both ways at the same time 5 Simplex data transmission (Con’t) keyboard Television Mouse Radio Broadcasts Monitor 6 Half-duplex data transmission (Con’t) A walkie-talkie A two-way radio that has a push-to-talk button Browsing the internet (requests and responses) Universal Serial Bus (USB) 7 Full-duplex data transmission (Con’t) Video calls/video conferencing Audio calls Live chats 8 Data Communication System Components Protocol Protocol Data Channel Sender Receiver 9 Requirements for Communication Basic Requirements for Successful Communication ❏ Two or more parties (Sender & Receiver) ❏ Communication medium (Channel) ❏ Use of compatible standards (Protocols) For data communication to occur, the communicating devices must be part of a communication system made up of a combination of hardware and software. 10  Characteristics of Data Communication System Delivery The system must deliver data to the correct destination. Data must be received by the intended device or user and only by that device or user. Accuracy The system must deliver data accurately. The data that had been altered in transmission and left uncorrected are unusable. Timelines The system must deliver data in a timely manner. Data delivered late are useless. Timely deliver means delivering data as they are transmitted, in the same order they are sent, and without significant delay. Other ??? 11 Sending Data from Source to Destination Data is encoded and transmitted as signals in the transmission media. Based on the bit pattern of data, the sending side generates a signal on the selected transmission medium and then this signal propagates to the receiving end. The receiving side extracts data from this signal and reproduce in its original format. 12 Modern data communication If you want to bridge long distances, fiber optic technology is the right choice. If the installation of cables is expensive or impossible, wireless communication is the right choice for short and medium distances. If communication lines are not available, existing mobile radio networks for remote communication are a good alternative. 13  Network Components three of the most common are: Workstations Servers Hosts Client Computer1 (Host) Client Computer2 (Host) Switch File Server (Server/Host) Application Server (Server/Host) Network printer Desktop printer (Workstation/Host) 14  Types of Networks Types of networks can be identified by their scale or based on physical scope. WAN (Wide Area Network) MAN (Metropolitan Area Network) LAN (Local Area Network) 15  Local Area Network agroup of interconnected devices that is under the samea building. administrative control or contained within typically owned andmanaged by a single person or organization. ‘local’ refers to local consistent control rather than being physically close to each other. PC1 Printer Switch Server Scanner PC2 PC3 Free Powerpoint Templates 16  Wireless Local Area Network wireless devices are used to transmit and receive data using radio waves as the media. PC2 Printer PC1 Wireless Access Point Laptop1 Laptop2 Laptop3 17  Campus Area Network an interconnection of Local Area Networks. a network spread between multiple contiguous buildings within a single property. 18  Metropolitan Area Network a network spread multiple non-contiguous buildings within several buildings in the same city or town. Free Powerpoint Page 7 19 Templates  Wide Area Network interconnection of LANs in geographically separated locations, typically covering multiple cities and countries. The Internet is the largest WAN that composed of millioniss of interconnected LANs. A router connects LANs to a WAN. Most WANs (like the exist Internet) are or under collective distributed ownership and management. 20 What is intranet, internet and The internet ?? intranet – ☞ a single inter-connected network within one organization. ☞ built from concepts and technology used for the Internet, such as client-server computing and TCP/IP. ☞ uses HTTP, SMTP, FTP for the sharing of information internally. internet – ☞ also knows as the extranet. ☞ an extension of intranet. ☞ external users can access publicly available resources. The Internet – ☞ the largest collection of networks. ☞ provides resources accessible via the Internet. ☞ provide variety of services including world wide web and e-mail. 21  Virtual Private Network mechanism providing secure, reliable transport over Internet. data integrity and security are maintained and ensured using encryption and encapsulation. 22  Network Architectures the way a network shares resources and information is, directly maps to the particular architecture of the Network Operating System(NOS). two main types : Peer-to-Peer architecture Client/Server architecture PC1 PC2 PC1 Server Switch Switch PC4 PC3 PC3 PC2 Peer-to-Peer Network Client/Server Network 23  Peer-to-Peer Architecture every host will act as a server(the provider of resources) AND a client(the receiver of resources). do not have any central or special authority. Client/Server Client/Server organized into workgroups by the operating system. Eg : Windows XP, Windows Vista, Windows 7 ideal to connect up to 10 computers. easy to maintain and set up, and also cost effective. very little security because no central Client/Server Client/Server administrations. Peer-to-Peer architecture 24  Client/Server Architecture each host will act specifically as a server OR a client. a server is specified with a Network Operating system, which organize a domain network. Eg : Windows NT, Windows Server 2003, Windows Server 2008 server provides centralized Client Client administration, managing the whole network and perform multiple duties. high security, performance and reduced network traffic. updates to that data are far easier. Client Domain network may have 10 to 5000 Server users attached to a server. Client/Server architecture 25  Network Topologies Defines the specific characteristics of a network. Can be physical or logical. Physical topologies: ▪ Bus Physical ▪ Ring Network ▪ Star Topologies ▪ Extended Star ▪ Mesh 26 Bus topology ▪ Each host is connected to a single bus cable. ▪ Signal travels in both directions to all hosts connected on the bus cable until it finds the intended destination. ▪ Bus can be the single point of failure. T-connector ▪ Easy to install and is not expensive. ▪ Hard to troubleshoot. Bus Terminator cable Bus Topology 27 CSMA/CD( Carrier Sense Multiple Access with Collision Detection 1 2 checks for presence If clear, proceed of a digital signal with transmission 3 checks for presence of a digital signal JAM JAM 4 4 JAM 5 Collision wait a while detected before attempting to transmit again 28 Ring topology ▪ Each host is connected to the network in a closed loop or a ring. ▪ A token, travels around the ring, Stopping at each host, which grants permission to send data. ▪ Copes with heavy Traffic better than Bus system, and also Covers great distance. ▪ The failure of one Station will cause the entire network to Fail. 29 Star topology ▪ Most common computer topology. ▪ Each host has a cable segment that attaches directly to the Central connection point. ▪ Easy to troubleshoot and more scalable. ▪ Problem in one Segment will only affect that host. ▪ Central connection point represents a single point of failure. 30 Extended-star topology ▪ A star network with an Extended Star Topology additional networking device connected to the main central connection point. 31 Mesh topology ▪ Many redundant interconnections between network nodes. ▪ Increased reliability and efficiency, but are very expensive and complex. Partial-Mesh Topology Full-Mesh Topology 32 Thank you 33