Computer Networks (ITDC-208) PDF

Computer Networks (ITDC-208) Dr. Mohit Kumar Assistant Professor Department of IT 1  Syllabus  Unit 1: Introduction: Introduction to C...

Computer Networks (ITDC-208) Dr. Mohit Kumar Assistant Professor Department of IT 1  Syllabus  Unit 1: Introduction: Introduction to Computer Networks History, Network Hardware, Network Software, OSI and TCP/IP reference models.  Unit 2: Physical Layer: Guided Transmission Media, Wireless Transmission, Communication Satellites, The Public Switched Telephone Network.  Unit 3: Data Link Layer: Data Link Layer Design Issues, Error Detection and Correction, Elementary Data Link Protocols, Sliding Window Protocols, Example Data Link Protocols. Medium Access Control Layer: The Channel Allocation Problem, Multiple Access Protocols, Ethernet, Wireless Lans, Broadband Wireless, Bluetooth, RFID, Data Link Layer Switching. 2  Unit 4: Network Layer: Network Layer Design Issues, IP, Routing Algorithms, Congestions Control Algorithms, Quality of Service, Routing Information Protocol  Unit 5: Transport Layer: The Transport Service, Elements of Transport Protocols, Flow and Congestion Control, The Internet Transport Protocol: UDP, TCP.  Unit 6: Application Layer: Hyper Text Transfer Protocol, File Transfer Protocols and Trivial File Transfer Protocol, Simple Mail Transfer Protocol, Domain Name Service, Telent, Secure shell, Network File System, Simple Network Management Protocol, Dynamic Host Configuration Protocol, Multipurpose Internet Mail Extensions, Post Office Protocol. 3  Course Objectives  1. Understand computer network basic, different models used for study of computer networks, ability to identify different designs, understanding of the issues surrounding wired and wireless Networks.  2. Design, calculate, and apply subnet masks to fulfill networking requirements and building the skills of routing mechanisms.  3. Analyze the features and operations of various application layer protocols such as Http, DNS, SMTP and FTP.  4. Analyze the requirements for a given organizational structure and select the most appropriate networking architecture and technologies  5. Familiarity with the basic protocols of computer networks, and how they can be used to assist in network design and implementation. 4  Course Outcomes  CO 1. Build an understanding of the fundamental concepts of computer networking.  CO 2. Familiarize the student with the basic taxonomy and terminology of the computer networking area. Introduce the student to advanced networking concepts, preparing the student for entry into advanced courses in computer networking.  CO 3. Allow the student to gain expertise in some specific areas of networking such as the design and maintenance of individual networks.  CO 4. Understand network security and define various protocols such as FTP, HTTP, Telnet, DNS 5  Recommended Books  1. Andrew S. Tanenbaum, “Computer Networks” Ed Pearson Education 4th Edition, 2010.  2. James F. Kurose and Keith W. Ross, “Computer Networking” Pearson Education, 2012.  3. William Stalling, “Data and Computer Communication”, Pearson Education, 7th Edition, 2nd Indian Reprint 2010.  4. Behrouz A. Fourouzan, Data Communications and Networking, 2/e Tat McGraw-Hill, 2006. 6 Questions  Why networks? And What is the motive of networks? Efficient Communication: Resource Sharing: Scalability and Flexibility Cost Reduction: Automation NIT Jalandhar 7 Components of Networks? Connecting devices Transmission Media Protocols and Software Components Network Topology: Network Services and Software: Firewall Data and Information Bennett University 8  Data Communication Model  Basically, it is used to exchange the data between two devices via some form of transmission medium.  The data is exchanged in the form of a bit stream or signal.  Data Communication has two types- Local and Remote  Fundamental characteristics are:  Accuracy  Delivery  Timelines  Jitter 9  Components of a data communication system Figure: Five components of data communication: Protocols, sender unit, receiver unit, medium and message NIT Jalandhar 10  Data flow Figure: Three modes of data flow: simplex, half duplex,11full duplex  Data flow  Simplex  Unidirectional flow at all times  Keyboard and monitor  Half-duplex  Unidirectional flow at a particular instant of time  Walkie-Talkie  Full-duplex  Bi-directional flow at all times  Telephones NIT Jalandhar 12  Networks  A network is the interconnection of a set of devices capable of communication. A device can be computer, laptop, phone etc.  Network Applications  Resource sharing such as printers and storage devices  Exchange of information by using Web or Internet  Video conferences  Instant messaging  Etc.  Network criteria are:  Performance  Reliability  Security NIT Jalandhar 13  Type of Connections Figure: Point-to-point and Multi-point links NIT Jalandhar 14  Types of links  Point-to-point Dedicated link between two points Example: IR remote for TV  Multi-point More than two devices share the same link – Spatial sharing: Several devices use the link simultaneously – Time sharing: Devices take turns in time, to share the link NIT Jalandhar 15  Network topology Network Topology is schematic description of a network arrangement, connecting various nodes through lines of connection. Figure: 4 basic network topologies NIT Jalandhar 16 A fully connected mesh topology (five devices) NIT Jalandhar 17  Mesh  In this every device has a dedicated p-2-p link to every device.  We need n(n−1)/2 duplex mode links.  Each device on network must have (n − 1) I/O ports.  It eliminates the traffic problem.  Mesh topology is robust. Even if one link is unusable , it does not effect the entire network.  The system has advantage of privacy & security.  Easy fault identification & correction  The main disadvantage is more cabling & large no. of I/O ports required.  Example: Telephone regional office NIT Jalandhar 18  A star topology connecting four stations NIT Jalandhar 19  Star  Each device has a dedicated P-2-P link only to central controller called as hub.  It does not allow direct traffic between devices. The controller acts as an exchanger.  If one sends data to another, it sends data to the controller, which then relay the data to another connected device.  In this each device needs only 1 I/O port.  The main disadvantage is that if the hub goes down then the entire network is dead. NIT Jalandhar 20 A bus topology connecting three stations NIT Jalandhar 21  Bus  It is a multi point communication system.  One long cable acts as backbone to link all the devices in the network.  Nodes are connected to bus cable by drop lines and taps.  Advantage: Nodes can be connected and disconnected with ease Each node requires just one I/O port  Disadvantage: As the signal travels along bus some of its energy is transformed into heat. So the signal becomes weaker & weaker as it travels farther & farther. It is difficult to fault isolation and reconnection. If there is fault or break in bus line then all the transmission will stop. NIT Jalandhar 22 A ring topology connecting six stations NIT Jalandhar 23  Ring  Each device has a dedicated P-2-P connection with only two devices on either sides.  A signal passes along the ring in one direction only, from device to device, until it reaches its final destination.  In this each device is incorporated with repeater, when a device receives a signal intended for another device, its repeater regenerates the bits and passes them along.  Unidirectional traffic is a disadvantage, a break in the ring can disable the entire network. NIT Jalandhar 24 A hybrid topology: a star backbone with three bus networks NIT Jalandhar 25  Categories of Networks  Generally, networks are distinguished based on their geographical span.  Some of the different networks based on size are:  Local area network (LAN)  Metropolitan area network (MAN)  Wide area network (WAN)  Some of the different networks based on their main purpose are:  Storage area network (SAN)  Enterprise private network (EPN)  Virtual private network (VPN) NIT Jalandhar 26  History of Networks  A computer network is a group of computers that has the potential to transmit, receive and exchange voice, data, and video traffic.  A network connection can be set up with the help of either cable or wireless media.  The history of computer networks dates back to the 1950s and 1960s when early computing systems began to emerge, and researchers started to explore the possibility of connecting computers to share resources and data.  One of the first significant milestones was the development of the ARPANET (Advanced Research Projects Agency Network) in 1969. 27  In the 1970s, the invention of packet switching by Paul Baran and Donald Davies became a pivotal moment in network history.  Packet switching allowed data to be broken into smaller packets and sent independently across various paths in a network, making data transmission more efficient and resilient.  The 1980s saw the development of key networking protocols such as TCP/IP (Transmission Control Protocol/Internet Protocol), which provided a standardized way for different networks to communicate.  For using TCP/IP, ARPANET finished the transition. The first DNS implement by Jon Postel and Paul Mockapetris in 1983. Bennett University 28  The first network switch was developed and introduced by a U.S. network hardware company named Kalpana in 1990.  In 1996, an IPv6 was introduced as an improvement over IPv4, as well as embedded encryption, improved routing.  In June 1997, the 802.11 standards, containing transmission speeds up to 2 Mbps, for Wi-Fi were introduced.  Throughout the 1990s and early 2000s, the internet grew exponentially with the rise of the World Wide Web (WWW), and networking technologies evolved to accommodate increasing demands for faster and more reliable communication. Bennett University 29