Welcome BENG 4522 Data Communications Computer Network Semester

Welcome ! BENG 4522 Data Communications & Computer Network Semester 1 2008/2009 Zulhani Bin Rasin B-2/9 Office : 06 -5552291 H/p : 012 -3767263 Email : zulhani@utem. edu. my Beng 4522. wordpress. com BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 1

Chapter 1 : Introduction to Computer Networks n Outline q q q Communication model Type of network Network models Network components Network topology Network technology and applications BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 2

1. 0 : The definition n Computer Network – an interconnected collection of devices (computers) which are : q Cooperative n n q Autonomous n n q Cooperative action is required between components No master-slave relationships All components are capable of independent action Any resource is capable of refusing requests Mutually Suspicious n Components verify requests BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 3

1. 1 : Communication Model BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 4

1. 1 : Communication Model n Source q n Transmitter q n Carries data Receiver q n Convert data a transmittable signals Transmission system q n Generate data to be transmitted Convert back the received signals in to the original data Destination q Takes the incoming data BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 5

1. 1 : Communication Model BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 6

1. 2 : Communication tasks n Task in communication model q q q q Transmission system utilization Interfacing Signal generation Synchronization Exchange management Error detection and correction Flow control Addressing Routing Recovery Message formatting Security Network management BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 7

1. 2 : Communication tasks n Transmission system utilization q q q n Interfacing q n Maximizing the use of transmission facilities that typically shared among numbers of communication device in most efficient way. Multiplexing for capacity allocation of a transmission medium. Congestion control to avoid system overwhelming by excessive demand. Depends on the use of electromagnetic signals propagated over the medium. Signal generation q q Capable of being operated - nature of signal must conform Interpretable as data at the receiver to the requirements of the transmission system BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 8

1. 2 : Communication tasks n synchronization q q q n Exchange management q n Various convention of queuing system, amount and format of data, contingencies methods for error. Error detection and correction q n The art of making clocks tick together. Timing must be synchronized between the transmitter and the receiver. Transmission time delay is essential. To guard against loss or damage of data and control information. Flow control q Function performed by a receiving entity to limit the amount or rate of data that is sent by a transmitting entity, avoid overwhelming the transmission system. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 9

1. 2 : Communication tasks n addressing q n Routing q n Techniques for selecting and maintaining a path through the network. Recovery q n Indication of the identity of the transmitter and intended destination. Objective : resume activity at point of interruption or restore to original state. Message formatting q Agreement between both parties as to the format of data exchanged i. e. in binary converted to characters. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 10

1. 2 : Communication tasks n security q n Measure of security to avoid intrusion against the exchange of information over the transmission system. Network management q Capabilities to configure, monitor, provision and expand the whole network. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 11

1. 3 : Components in data communications of computer network n Protocol q q set of rules that manage the data transactions/communications between the devices. Agreement between the communicating devices - format of data, medium of transmission and speed of transmission etc. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 12

1. 4 : Networking n n Physical structure Types of connection q q 2 or more devices connected together through links. Link is pathway that transfer data from one device to another. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 13

1. 4 : Networking n Point-to-point link BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 14

1. 4 : Networking n Multipoint (multidrop) BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 15

1. 4 : Networking n Point-to-point communication is not usually practical. q q n Devices are too far apart. Large set of devices would need impractical number of connections. Solutions is a communication network (using multipoint link) q q q Local Are Network (LAN) Wide Area Network (WAN) Metropolitan Area Network (MAN) BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 16

1. 4. 1 Type of Networks n Categories of networks q Determined by its size, ownership, distance covered, and physical architecture. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 17

1. 4. 1. 1 Local Area Network (LAN) n Single Building LAN q Usually privately owned and links the devices in a single office, building or campus. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 18

1. 4. 1. 1 Local Area Network (LAN) n Multiple Building LAN q q q Size limited to a few kilometers. Common topologies are bus, ring and star. High data rate – 4/10/16 Mbps to 100 Mbps or gigabits. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 19

1. 4. 1. 2 Metropolitan Area Network (MAN) n Extend over entire city, maybe wholly owned by a private company, popular services SMDS. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 20

1. 4. 1. 3 Wide Area Network (WAN) n n n Long-distance transmission over large geographical areas (continent/world). Utilize public, leased or private communication in combinations. An enterprise network is a WAN owned by one company. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 21

1. 4 LAN/MAN/WAN Comparison LAN distance medium speed MAN WAN -limited (up to 2500 meters) -generally covers towns and cities (50 km) -covers large distances (state, countries, continents - optical fibers, coaxial cables, twisted pair, wireless -optical fibers, cables, wireless satellite -high speed (0. 2 Mbps ~ 1 Gbps) -low latency -high speed < 100 Mbps -typical latency < 1 ms -typical speed 20 ~ 2000 kbps -typical latency : 100 ms ~ 500 ms BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 22

1. 4. 2 Network Topology n n The study of location 2 types of topology q q n n Physical – describes the wiring scheme Logical – describes how data flows through the network Network can have different physical and logical topologies Type of topologies q q q q q Fully connected (mesh) Bus Ring Star Extended star Tree Irregular Cellular Hybrid BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 23

1. 4. 2. 1 Mesh Topology n Mesh topology q q q Every node is linked directly to every other node. Not practical for geographically distributed users. Redundant connection, should any link fail to function, information can flow through any number of other links to reach its destination. Very costly (N users require N times (N-1) links !). Simple, straight forward operation. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 24

1. 4. 2. 2 Bus Topology n Bus topology q q q Single cable connects all computers. Each computer has connector to shared single cable (called as bus or backbone). Terminators signal the physical end to the segment. Logical – all devices can see all communications. Physical – each device is on the same wire. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 25

1. 4. 2. 2 Bus Topology n Advantages q q q n Works well for small networks. Relatively inexpensive to implement. Easy to add to it. Disadvantages q q q Management costs can be high. Potential for congestion with network traffic. Breakdown in the bus cable brings the entire network down. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 26

1. 4. 2. 3 Ring Topology n Ring topology q q q Computers connected in cascading order to make a closed loop ring. The source station transfers the information to the next station on the ring, which checks the address of the information. Continuous path for data with no logical beginning or ending point, and thus no terminators. Logical – each station passes data to the adjacent station. Physical – devices wired in a daisy chain. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 27

1. 4. 2. 3 Ring Topology n Advantages q q n Easier to manage, easier to locate a defective node or cable problem. Well-suited for long distance on a LAN. Handles high volume network traffic. Enables reliable communication. Disadvantages q q Expensive (complex hardware with expensive NIC) Requires more cable and network equipment at the start. If a link or station breaks down, the entire network is disabled. Adding new client disrupts the entire network. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 28

1. 4. 2. 4 Star Topology n Star Topology q q Oldest and most common network design. Multiple nodes attached to a central hub. Physical – all nodes connected to a center node. Logical – all data passed through the center node. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 29

1. 4. 2. 4 Star Topology n Advantages q q q n Easy to design and install. Low startup costs and easy to manage and maintain. Layout is easy to modify and troubleshoot. Reliable. Easily scalable (easy to add hosts. Disadvantages q q Hub is a single point of failure. Requires more cabling than the bus. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 30

1. 4. 2. 5 Extended-Star Topology n E-star topology q An extended star topology repeats a star topology, where each node that links to the center node, is also the center of another star. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 31

1. 4. 2. 6 Tree & Irregular Topologies n Tree Topologies q q n Similar to the extended star topology, the primary difference being that it does not use one central node. Instead, it uses a trunk node from which it, then, branches to other nodes. Ex : telephone networks Irregular Topologies q There is no obvious pattern to the links and nodes. The wiring is inconsistent; the nodes have varying numbers of wires leading from them. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 32

1. 4. 2. 7 Cellular Topologies n Cellular Topologies q q Consists of circular or hexagonal areas, each of which has an individual node at its center. Used in wireless cellular networks. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 33

1. 4. 2. 8 Hybrid Topologies BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 34

1. 4. 3 Topology-Design Related Issues n n n Cost of installation and maintenance Redundancy Reliability (no single point of failure) Expandability (scalability) Need for switching q n Need for routing q n Process of directing traffic through the network based on a pre-defined route. Process of finding the best route for the traffic. Delay BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 35

1. 4. 4 Network Model n Model – functions and service provided by the network BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 36

1. 4. 4. 1 Peer-to-Peer Network n Peer-to-peer network q q q There are no dedicated servers or hierarchy among the computers. All the computers are equal and therefore known as peers. Each computer serves as client/server and there is no one assigned to be an administrator responsible for the entire network. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 37

1. 4. 4. 2 Client/Server Network n Client/Server Network q q q A small number of computers are designated as centralized servers and given the task of providing services to a large number of user machines called clients. Servers are usually a powerful computers with a lot of memory and storage space, and fast network connections. Server software runs on server hardware and client software is used on client computers that connected to those servers. Most of the interaction on the network is between client and server, and not between clients. Server software is designed to efficiently respond to requests, while client software provides the interface to the human users of the network. BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 38

1. 4. 4. 2 Client/Server Network n Client/Server Network BENG 4522 Data Communications & Computer Networks Chapter 1 : Introduction to Computer Network 39

1. 5 Networking Technology n Technologies q q q Ethernet Fast Ethernet Token Ring FDDI ATM DQDB X. 25 Frame Delay IP-Packet Switching ISDN x. DSL etc BENG 4522 Data Communications & Computer Networks n Applications q q q q Hypertext Transfer Protocol (HTTP) -WWW File Transfer Protocol (FTP) Supervisory Control and Data Acquisition (SCADA) Network Monitoring System (NMS) Terminal Access – Telnet E-learning E-commerce etc Chapter 1 : Introduction to Computer Network 40