CS452 Data Communications Lecture Notes PDF

CS452: Data Communications  Agenda  Course Objectives  Course Books  Course Content  Course Evaluation  Projects Course Objectives  To provide a comprehensive overview of the basic principles and terminologies in data communication.  To explore the r...

CS452: Data Communications  Agenda  Course Objectives  Course Books  Course Content  Course Evaluation  Projects Course Objectives  To provide a comprehensive overview of the basic principles and terminologies in data communication.  To explore the role of the physical layer in data communication.  Analyze the principles and techniques of both digital and analog transmission. Course Book Course Content  Overview: (Revision)  Chapter 1: Introduction  Chapter 2: Network Models  Physical Layer  Chapter 3: Introduction to Physical Layer  Chapter 4: Digital Transmission  Chapter 5:Analog Transmission  Chapter 6: Bandwidth Utilization: Multiplexing and Spectrum Spreading Course Evaluation Code Course Title Hours Marks No. Lect. Lab. Written Oral Test Total Exam &Lab CS452 Data 3 3 80 20 20 120 Communications Chapter 1- Introduction Agenda DATA COMMUNICATIONS Components Data Flow NETWORKS Network Criteria Network Connections Network Topology Network Types Internet Data communication Is the exchange of data between two devices via some form of transmission medium. Effectiveness of data communication system depends on: 1. Delivery 2. Accuracy 3. Timeliness 4. Jitter 9 Effectiveness of data communication system depend on: 1. Delivery :  The system must deliver data to correct destination.  Data received by the intended user only. 2. Accuracy:  The system must deliver data accurately (no change). 10 Effectiveness of data communication system depend on: 3. Timeliness:  The system must deliver data in timely manner.  Data arrived late are useless.  In the case of (video and audio), delivering data in the same order that they produce without delay (Real time transmission). 11 Effectiveness of data communication system depend on: 4. Jitter:  Variation in the packet arrival time.  For example: let us assume that video packets are sent every 30 ms. If some of the packets arrive with 30-ms delay and others with 40-ms delay, an uneven quality in the video is the result. 12 Data Communication Components  A data communication system is made up of five components. 13 Data Communication Components 1. Message: the information (data) to be communicated – Consist of text, numbers, pictures, audio, or video 2. Sender: the device that sends the data message – Computer, workstation, telephone handset, video camera. 3. Receiver: the device that receives the message – Computer, workstation, telephone handset, television. 4. Medium: The physical path by which a message travels from sender to receiver. – twisted pair, coaxial cable, fiber-optic, radio waves 5. Protocol: a set of rules that govern data communications – HTTP, FTP, TCP, UDP 14 Data Flow Communication between two devices can be:  Simplex  Half-Duplex  Full-Duplex 15 Simplex  The communication is unidirectional.  Only one device on a link can transmit; the other can only receive.  Use the entire capacity of the channel to send data.  Example: Keyboards, Monitors. Data 16 Half-Duplex  Each station can both transmit and receive, but not at the same time.  When one device is sending, the other can only receive, and vice versa.  The entire capacity of a channel is taken over by the transmitting device.  Example: Walkie-talkies. Data Data 17 Full-Duplex  Both stations can transmit and receive at same time.  Signals going in either direction sharing the capacity of the link.  Sharing can occur in two ways:  Link has two physically separate transmission paths one for sending and the other for receiving.  The capacity of the channel is divided between signals travelling in both directions.  Example: Telephone network. Data Data Networks Network: A set of devices (nodes) connected by communication links. Node: computer, printer, … Network Criteria : – Network must meet a certain number of criteria – The most important of the network criterions are: Performance Reliability Security 19 Performance Can be measured in many ways:  Transit time (low) : A mount of time required for a message to travel from one device to another.  Response time (low) : Elapsed time between an inquiry and a response.  Throughput (high): a measure of how much data can be transferred from one location to another in a given amount of time.  Delay time (low). 20 Performance Depends on : 1. Number of users: large number slow response time. 2. Type of transmission medium: fiber-optic cabling faster than others cables. 3. Capabilities of the connected hardware: affect both the speed and capacity of transmission. 4. Efficiency of the software: process data at the sender and receiver and intermediate affects network performance. 21 Network Criteria Reliability is measured by:  Frequency of failure.  Recovery time of a network after a failure. Security:  Protecting data from unauthorized access.  Protecting data from damage and development.  Implementing policies and procedures for recovery from breaches and data losses. 22 Network Connection A link is a communications pathway that transfers data from one device to another.  For communication to occur, two devices must be connected in some way to the same link at the same time. There are two possible types of connections:  point-to-point.  multipoint. 23 Point-to-Point connection Dedicated link between two devices. Entire capacity of the link is reserved for transmission between those two devices. 24 Multipoint (multidrop) Connection More than two devices share a single link.  Capacity is shared.  Channel is shared either spatially or temporally  Spatially shared: if devices use link at same time.  Timeshared: if users must take turns. 25 Networks Topology The way a network is laid out physically. Two or more links form a topology. Four topologies : Mesh, Star, Bus, and Ring. 26 Mesh Topology Every link is dedicated point-to-point link The term dedicated means that the link carries traffic only between the two devices it connects. To link n devices fully connected mesh has: n ( n - 1) / 2 physical channels (Full-Duplex) Every Device on the network must have n - 1 ports Example: How many link and I/O port for Network has 4 devices in mesh 27 Example:  8 devices in mesh has links:  number of links = 8 (8-1)/2 = 28  number of ports per device = n – 1 = 8 –1 = 7 Star Topology is a topology for a Local Area Network (LAN). all nodes are individually connected to a central connection point, like a hub or a switch. 29 Bus Topology It is multipoint One long cable acts as a backbone. Used in the design of early LANS. 30 Ring Topology Each device has dedicated point-to-point connection with only the two devices on either side of it. A signal is passed along the ring in one direction from device to device until it reaches its destination. Each devices incorporates a Repeater. 31 Hybrid Topology Example: having a main star topology with each branch connecting several stations in a bus topology. 32 Network Types Networks infrastructures can vary greatly in terms of:  The size of the area covered.  The number of users connected.  The number and types of services available. Network Types  LAN “Local Area Network”  WAN “Wide Area Network” 33 LAN “Local Area Network” A LAN is a network that connects computers and devices within a limited geographical area, such as a home, office, or school. Typically covers a small area, usually confined to a single building or a group of nearby buildings. Usually owned and maintained by a single organization or individual. Examples: A home Wi-Fi network, office networks, or networks within a school. 34 WAN “Wide Area Network”  A WAN is a network that covers a broad area, often connecting multiple LANs over large distances.  Can span cities, countries, or even continents.  Typically owned and operated by multiple organizations or telecommunications companies.  The Internet The Internet is a vast global network that connects millions of private, public, academic, business, and government networks worldwide. It is a network of networks, effectively covering the entire globe. Not owned by any single entity; it is a collaborative effort between various organizations, governments, and service providers. 36 The Internet Exercises True or False 1. A protocol is a set of rules governing communication between devices. 2. Simplex communication allows data to flow in both directions simultaneously. 3. In a half-duplex system, two devices can communicate with each other, but not at the same time. 4. The Internet is a private network within a small area. 5. In a bus topology, all devices share a common backbone cable. True or False 1. A protocol is a set of rules governing communication between devices. 2. Simplex communication allows data to flow in both directions simultaneously. 3. In a half-duplex system, two devices can communicate with each other, but not at the same time. 4. The Internet is a private network within a small area. 5. In a bus topology, all devices share a common backbone cable. Which type of network is typically confined to a single office, building, or campus? a) WAN b) LAN c) Internet d) MAN In a data communication system, what is the "message"? a) The device sending the data b) The rules that govern communication c) The information being transmitted d) The medium through which the data travels Which network topology involves every device having a dedicated connection to every other device? a) Star b) Bus c) Mesh d) Ring Task Task :  What is the OSI model, and how does it work?  How does the TCP/IP layered model function, and what are its key components?  What are the differences between the OSI model and the TCP/IP model in terms of layers and functions? Practical Python Code: Simple Data Communication System  Python code example that simulates a simple data communication system.  This code demonstrates the concepts of sending and receiving messages between a sender and receiver while considering the effectiveness factors like accuracy and timeliness. Simple Chat Application Description: Create a basic chat application where two users can send messages to each other over a network. Technologies: Use Python with sockets for networking, and a simple command-line interface for user interaction. Features: Send and receive text messages. Show timestamps for messages. Allow for multiple messages to be sent in a session. Sheet Sheet 1. Identify the five components of a data communications system. 2. What are the three criteria necessary for an effective and efficient network? 3. What are the advantages of a multipoint connection over a point-to-point connection? 4. What is the difference between half-duplex and full-duplex transmission modes? 5. Name the four basic network topologies and cite an advantage of each type. 51 Sheet 6. For n devices in a network, what is the number of cable links required for a mesh, ring, bus, and star topology? 7. What are some of the factors that determine whether a communication system is a LAN or WAN? 8. What is an internet? What is the Internet? 9. Why are protocols needed? 52  How many layers are there in the OSI model? A) 4 B) 5 C) 6 D) 7  Which of the following layers is responsible for routing and logical addressing in the OSI model? A) Data Link Layer B) Transport Layer C) Network Layer D) Physical Layer  Which layer in the TCP/IP model is equivalent to the combination of the OSI’s Application, Presentation, and Session layers? A) Internet Layer B) Application Layer C) Transport Layer D) Link Layer  In the OSI model, which layer is responsible for reliable data transfer and error recovery? A) Network Layer B) Session Layer C) Transport Layer D) Data Link Layer  In the TCP/IP model, which protocol provides connectionless, unreliable communication between applications? A) TCP B) HTTP C) UDP D) FTP  Which layer in the OSI model is primarily concerned with the physical connection and transmission of raw data over a medium? A) Data Link Layer B) Physical Layer C) Session Layer D) Application Layer  Which of the following is NOT a layer in the TCP/IP model? A) Application Layer B) Presentation Layer C) Internet Layer D) Transport Layer  The OSI model was developed by which organization? A) IETF B) ISO C) IEEE D) ITU  In which layer of the TCP/IP model does the IP protocol operate? A) Link Layer B) Transport Layer C) Internet Layer D) Application Layer  What is the primary purpose of the Session layer in the OSI model? A) Data formatting and encryption B) Establishing, managing, and terminating connections C) Data routing and packet forwarding D) Error detection and correction