Week_1_Class_2.pdf

Instructor Profile Dr. Qaisar Shaheen PhD. MCSE(Microsoft Certified System Engineer). Assistant Professor/HoD Department of Computer Science & IT The Islamia University of Bahawalpur – Rahim Yar Khan Campus [email protected] Google Scholar Advance Computer Networ...

Instructor Profile Dr. Qaisar Shaheen PhD. MCSE(Microsoft Certified System Engineer). Assistant Professor/HoD Department of Computer Science & IT The Islamia University of Bahawalpur – Rahim Yar Khan Campus [email protected] Google Scholar Advance Computer Networks  Text Book Computer Networking: A Top-Down Approach Featuring the Internet, by James F. Kurose and Keith W. Ross Data Communication and Computer Networks by Behrouz A. Forouzan. 3 Network Overview What must a network provide ? Connectivity Cost-effective sharing Functionality Performance How are networks designed and built ? Layering Protocols Standards 4  Data Communications The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data. The term telecommunication means communication at a distance. Data communications are the exchange of data between two devices via some form of transmission medium such as a wire or a wireless. 1.5  Components of a data communication system 1.6  Data Communications The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data. The term telecommunication means communication at a distance. Data communications are the exchange of data between two devices via some form of transmission medium such as a wire or a wireless. 1.7  Components of a data communication system 1.8  A Simple Communication Model 1.9  Characteristics of a Data Communication System Delivery Data must be received by the intended device or user and only by that device or user Accuracy The system must deliver the data accurately. Data that have been altered in transmission and left uncorrected are unusable. Timeliness The system must deliver data in a timely manner. Data delivered late are useless Jitter Jitter refers to the variation in the packet arrival time. It is the uneven delay in the delivery of audio or video packets. 1.10  What is Computer Networks Set of serial lines to attach Computers/Nodes to main frame? Land line Telephone network carrying voice traffic? TV cable network for carrying video signal? 1.11  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. Support to a wide range of applications (Video, Audio, Text) 1.12  Application – Consumer of Networks On a simple click, several messages may be exchanged over the internet (Protocol, devices Communication) In a web browser, up to 17 messages may be exchanged. up to six messages to translate the server name (DNS) three messages to set up a TCP connection four messages to send HTTP “get” request + response four messages to tear down the TCP connection Millions of messages (click) transported at the same time. Efficient transport. Reliable delivery. To deliver the destination. 1.13  Why need complex Networks Streaming Video & Audio is an emerging application. Video on demand (one-way data transfer). Video Conferencing (very tight time constraints). Diversity of application needs the complexity of the network. 1.14  Network Criteria A network must be able to meet a certain number of criteria: Performance Depends on Network Elements Measured in terms of Delay and Throughput How much data is successfully transferred from source to destination. Delay refers to the amount of time for transfer data from source to destination. 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 1.15  Physical Structure of the network Link Type of Connection Point to Point - single transmitter and receiver Multipoint - multiple recipients of single transmission 1.16  Types of connections: point-to-point and multipoint 1.17  Building blocks for Network Nodes: PC, Special propose hardware. Host. Switches. Links: Coax Cable, Optical Fiber. 1.18  Physical Structures Links + Nodes=Topology Physical Topology (Physical layout of Network) Connection of devices Type of transmission - unicast, multicast, broadcast 1.19  Categories of topology 1.20  Figure 1.5 A fully connected mesh topology (five devices) 1.21  A star topology connecting four stations 1.22  A bus topology connecting three stations 1.23  A ring topology connecting six stations 1.24  A hybrid topology: a star backbone with three bus networks 1.25  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 1.26  Local Area Networks (LANs) Usually Privately owned Connects some hosts in a single office, building, or campus Can be as simple as two PCs and a printer in someone’s home, office. Can extend throughout a company Host Address 1.27  An isolated LAN connecting 12 computers to a hub in a closet 1.28