Computer Networks Lecture Slides PDF

Computer Networks Networks: Introduction 1 Course Objectives Networks: Introduction 2  Course Objectives 1. To develop an understanding of modern network architectures from a design and performance perspective. 2. To clarify network terminology. 3. To provide an oppor...

Computer Networks Networks: Introduction 1 Course Objectives Networks: Introduction 2  Course Objectives 1. To develop an understanding of modern network architectures from a design and performance perspective. 2. To clarify network terminology. 3. To provide an opportunity to do network programming using TCP/IP. 4. To expose students to emerging technologies and their potential impact Networks: Introduction 3 Introduction Networks: Introduction 4 The Internet: a “nuts and bolts” view Billions of connected mobile network computing devices: national or global ISP  hosts = end systems  running network apps at Internet’s “edge” Packet switches: forward local or packets (chunks of data) Internet regional ISP  routers, switches home network content Communication links provider network  fiber, copper, radio, satellite datacenter network  transmission rate: bandwidth Networks enterprise  collection of devices, routers, links: network managed by an organization Introduction: 1-5 “Fun” Internet‐connected devices Tweet‐a‐watt: monitor energy use bikes Pacemaker & Monitor Amazon Echo Web‐enabled toaster + IP picture frame weather forecaster Internet refrigerator Slingbox: remote cars control cable TV Security Camera AR devices sensorized, scooters bed mattress Fitbit Gaming devices Others? Internet phones diapers Introduction: 1-6 The Internet: a “nuts and bolts” view mobile network 4G  Internet: “network of networks” national or global ISP Interconnected ISPs  protocols are everywhere IP Streaming Skype video control sending, receiving of messages local or regional e.g., HTTP (Web), streaming video, ISP Skype, TCP, IP, WiFi, 4/5G, Ethernet home network content provider HTTP network  Internet standards datacenter network Ethernet RFC: Request for Comments TCP IETF: Internet Engineering Task enterprise Force network WiFi Introduction: 1-7  Network Definitions and Classification Preliminary definitions and network terminology Sample application paradigms Classifying networks by transmission technology Classifying networks by size (or scale) Classifying networks by topology Networks: Introduction 8  Preliminary Definitions Computer network :: [Tanenbaum] a collection of “autonomous” computers interconnected by a single technology. [LG&W] communications network ::a set of equipment and facilities that provide a service. In a distributed system the collection of independent computers appears to its users as a single coherent system. Networks: Introduction 9  Client-Server Applications Figure 1.1 A network with two clients and one server. Networks: Introduction 10  Client-Server Model Figure 1-2. The client-server model involves requests and replies. Networks: Introduction 11  Peer-to-Peer Applications Figure 1.3 In a peer-to-peer system there are no fixed clients and servers. Networks: Introduction 12  Mobile Network Users Figure 1.4. Combinations of wireless networks and mobile computing. Networks: Introduction 13  W1 T X Z W2 W Y Host Host L AP W3 M Host A 2 3 W4 4 1 Host 5 B 16 nodes 14 Host 11 J Host 12 17 C 15 6 10 13 7 Host 9 H Host 8 D Host G Host E Host F Networks: Introduction 14  K & R Networks: Introduction 15 DATA COMMUNICATIONS The term telecommunication means communication at a distance. The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data. Data communications are the exchange of data between two devices via some form of transmission medium such as a wire cable. Topics discussed in this section:  Components of a data communications system  Data Flow 1.16 Figure 1.5 Components of a data communication system Figure 1.6 Data flow (simplex, half-duplex, and full-duplex) NETWORKS A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. A link can be a cable, air, optical fiber, or any medium which can transport a signal carrying information. Topics discussed in this section:  Network Criteria  Physical Structures  Categories of Networks 1.19 Network Criteria Performance Depends on Network Elements Measured in terms of Delay and Throughput Reliability Failure rate of network components Measured in terms of availability/robustness Security Data protection against corruption/loss of data due to: Errors Malicious users 1.20  Physical Structures Type of Connection Point to Point - single transmitter and receiver Multipoint - multiple recipients of single transmission Physical Topology Connection of devices Type of transmission - unicast, mulitcast, broadcast 1.21  Classifying Networks by Transmission Technology broadcast :: a single communications channel shared by all machines (addresses) on the network. Broadcast can be both a logical or a physical concept (e.g. Media Access Control (MAC) sublayer ). multicast :: communications to a specified group. This requires a group address (e.g. – multimedia multicast). unicast :: a communication involving a single sender and a single receiver. point-to-point :: connections made via links between pairs of nodes. Networks: Introduction 22 Network Classification by Size Figure 1-7. Classification of interconnected processors by scale. Networks: Introduction 23  Categories of Networks Local Area Networks (LANs) Short distances Designed to provide local interconnectivity Wide Area Networks (WANs) Long distances Provide connectivity over large areas Metropolitan Area Networks (MANs) Provide connectivity over areas such as a city, a campus Network Classification by Size LANs {Local Area Networks} – Wired LANs: typically physically broadcast at the MAC layer (e.g., Ethernet, Token Ring) – Wireless LANs (WLANs) – Wireless Sensor Networks (WSNs) MANs {Metropolitan Area Networks} – campus networks connecting LANs logically or physically. – often have a backbone (e.g., FDDI [Fibre distributed data nterface] and ATM [Asynchronous Transfer Mode]) Networks: Introduction 25  Wired LANs transceivers       Ethernet bus Ethernet hub Copyright ©2000 The McGraw Hill Leon-Garcia & Widjaja: Communication Figure 1.17 Companies Networks Networks: Introduction 26  Wireless LANs (WLANs) Figure 1.8. (a) Wireless networking with a base station. (b) Ad hoc networking. Networks: Introduction 27 Metropolitan Area Networks Figure 1.9. A metropolitan area network based on cable TV. Networks: Introduction 28  MAN 1* a b 2 Metropolitan network A 4 consists of access 3 A subnetworks a, b, c, d. c d Hierarchical Network Topology National network A consists of regional  subnetworks .  Metropolitan network  A is part of regional Copyright ©2000 The McGraw Hill subnetwork . Companies Leon-Garcia & Widjaja: Communication Figure 1.8 Networks Networks: Introduction 29 Network Classification by Size WANs {Wide Area Networks} – also referred to as “point-to-point” networks. – ARPANET  Internet – usually hierarchical with a backbone. – Enterprise Networks, Autonomous Systems – VPNs (Virtual Private Networks). Networks: Introduction 30 Wide Area Networks (WANs) Figure 1.10.A stream of packets from sender to receiver. Networks: Introduction 31  net 3 G net 1 G G G = gateway G net 5 net 2 G net 4 G Copyright ©2000 The McGraw Hill internet - a network of networks Companies Figure 1.11 Leon-Garcia & Widjaja: Communication Networks Networks: Introduction 32  Network Classification by Topology Bus flow of data Bidirectional flow assumes baseband cable Repeater Networks: Introduction 33 Network Classification by Topology Ring Repeater Repeater Note - a ring implies unidirectional flow Networks: Introduction 34 Network Classification by Topology Tree Headend Networks: Introduction 35 Network Classification by Topology Star hub, switch or repeater Networks: Introduction 36 Network Classification by Topology Star W1 W2 AP W3 W4 Wireless Infrastructure Networks: Introduction 37