Data Communications and Networks

Data Communications and Networks

• 1.
  HNDIT1213 Data Communications andNetworks
• 2.
  Definition A network canbe defined as two or more computers connected together in such a way that they can share information and resources. Or Two or more computers or communication devices connected by transmission media and channels and guided by a set of rules for communication purpose that allows user to communicate with each other and share information and resources
• 4.
  Definition (cont..) A resourcemay be:  A file  A folder  A printer  A disk drive  Or just about anything else that exists on a computer.
• 5.
  Advantages of networking Connectivity and Communication  Data Sharing  Hardware Sharing  Internet Access  Internet Access Sharing  Data Security and Management  Entertainment  Sharing devices such as printers saves money.  Files can easily be shared between users.  Security is good - users cannot see other users' files unlike on stand- alone machines.  Data is easy to backup as all the data is stored on the file server.  Etc…
• 6.
  Disadvantages of networking Network Hardware, Software and Setup Costs  Hardware and Software Management and Administration Costs  Data Security Concerns  Managing a large network is complicated, requires training and a network manager usually needs to be employed.  If the file server breaks down the files on the file server become inaccessible.  Viruses can spread to other computers throughout a computer network.  There is a danger of hacking, particularly with wide area networks.  Etc..
• 7.
  kinds of networks Dependingon one's perspective, classify networks in different ways  Based on the transmission media : Wired (UTP, Coaxial cables, fiber-optic cables) and wireless  Based on the Network Size: LAN,WAN and MAN  Based on the management method: peer to peer, Client/Server  Based on the topology (Connectivity): Bus, Star, Ring
• 8.
  Types of Network(Basedon the Network Size)  Local Area Networks (LANs)  Wide Area Networks (WANs)  Metropolitan Area Network (MAN) Types of Networks
• 9.
  Local Area Networks(LANs)  A local area network is usually privately owned and links the devices in a single office, building, or campus  LANs are designed to allow resources to be shared (i.e., printers or applications programs )between PCs or workstations
• 10.
  Metropolitan Area Network(MAN)  A metropolitan area network is designed to extend over an entire city. It may be a single network  In addition, it may be a means of connecting a number of LANs into a larger network
• 11.
  Wide Area Network(WAN)  A wide area network (WAN) provides long-distance transmission of data, voice, image, and video information over large geographical areas that may comprise a country, a continent, or even the whole world.
• 13.
  Types of Networkin LAN (Based on the management method)  Peer-to-Peer Networks A peer-to-peer (P2P)network is created when two or more PCs are connected and share resources without going through a separate server computer  Client/Server Networks A computer network in which one centralized, powerful computer (called the server) is a hub to which many less powerful personal computers or workstations (called clients) are connected.
• 14.
  Peer-to peer Network
• 15.
  Peer-to peer Network
• 16.
  Advantages of Peer-to-peernetworking  Easy set up  Each connected computer can act as a server so no need for a dedicated server  Failure doesn’t affect all computers  Less expense  Less configuration and implementation time
• 17.
  Disadvantages of Peer-to-peernetworking  Easy access to any computer  Security is only as strong as whatever security is in place on each computer  Backup has to be done on each computer  No control of access to data as there is no server
• 19.
  Client/Server Network
• 20.
   Central management– all of the resources of the network are available from one server  Easy configuration – Systems on the network are simple to set up and can make troubleshooting easier  Scalability – because of a centralized system, it can be easy to add more resources & clients.  Security – There are fewer security issues to deal with as all of the information is stored on a server and it’s primarily the server that has to worry about securing data and setting permissions Advantages of Client/Server networking
• 21.
  Disadvantages of Client/Servernetworking  Server Faults – If there is a fault on the server all of the clients would go down too  Crashes – If the server cannot handle large amounts of traffic due to too many concurrent log-ins or file transfers, it can cause system crashes  Cost – Initial start-up costs can be expensive and you’d also have to have a systems administrator to configure and oversee the network
• 22.
  Peer-to-Peer Networks VersusClient/Server Client-Server Peer-Peer Complex to set up Simple to set up Requires technical expertise to set up and maintain Needs basic technical skills Server present No server present, each computer is a 'peer' of the others Centralized data and application management Each computer has its own data and applications loaded Uses a dedicated network operating system Uses standard operating system with network capabilities User access and authentication is managed centrally Fairly basic login authentication for each user
• 23.
  Data Communication The processof transferring data from one location to another is called Data Communication. Data formats – analog or digital Data travels across the medium Wired Medium Wireless Medium
• 24.
  characteristics of datacommunication The data communication system depends on 4 fundamental characteristics:  Delivery. The system must deliver data to the correct destination  Accuracy. The system must deliver data accurately  Timeliness. The system must deliver data in a timely manner  Jitter: jitter refers to the variation in the packet arrival time. It is the uneven delay in the delivery of packets.
• 25.
  Process/Components of adata communication  Message : The message is the information to be communicated. It can consist of text, number, pictures, sound, or video-or any combination of these (multimedia).  Sender /Transmitter: The sender is the device that sends the data message. It can be a computer, workstation, telephone handset, video camera, and so on.  Receiver : The receiver is the device that receive the message  Medium : The transmission medium is the physical path by which a message travels from sender to receiver. It can consist of twisted par wire, coaxial cable, laser, or radio wares (terrestrial or satellite microwave).  Protocol : A protocol is a set of rules that govern data communication. It represents an agreement between the communicating devices
• 28.
  Encoder and Decoder Incommunication systems, computers are used for senders and receivers. A computer works with digital signals. The communication channels usually use analog signals. The encoder and decoder are used in communication systems to convert signals from one from to another. Encoder: The encoder is an electronic device. It receives data from sender in the form of digital signals. It converts digital signals into a form that can be transmitted through transmission medium. Decoder: The decoder is an electronic device. It receives data from transmission medium. It converts encoded signals (i.e. analog signals) into digital form.
• 30.
  Interference  In datacommunications ,interference is anything which modifies, or disrupts a signal as it travels along a channel between a source and a receiver.  Interference is any barrier to the data communication.
• 31.
  Basic Communication/transmission Modes ofOperation There are three modes of transmission simplex, half duplex, and full duplex. Transmission mode describes the direction, of flow of signal between two connected devices.
• 32.
  Simplex  Simplex isone direction.  a network cable or communications channel can only send information in one direction; it's a “one-way street”
• 33.
  half duplex Technologies thatemploy half-duplex operation are capable of sending information in both directions between two nodes, but only one direction or the other can be utilized at a time.
• 34.
  full duplex Full-duplex datatransmission means that data can be transmitted in both directions on a signal carrier at the same time.
• 35.
  BASIS FOR COMPARISON SIMPLEX HALFDUPLEX FULL DUPLEX Direction of Communication Communication is unidirectional. Communication is two- directional but, one at a time. Communication is two directional and done simultaneously. Send/Receive A sender can send data but, cannot receive. A sender can send as well as receive the data but one at a time. A sender can send as well as receive the data simultaneously. Performance The half duplex and full duplex yields better performance than the Simplex. The full duplex mode yields higher performance than half duplex. Full duplex has better performance as it doubles the utilization of bandwidth. Example Keyboard and monitor. Walkie-Talkies. Telephone.
• 36.
  Data Communication :Applications e-mail, Voice mail,  File transfer, Document transfer,  Fund Transfer, e-commerce,  Software download  Tele-shopping, Tele-medicine, Telecommuting  Distance learning, Teleconferencing,  Long distance telephone calls, Chat,  Weather reports, Stock exchange information,News