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The document discusses the course Computer Networks-22MCA14 taught by Dr. Dattatreya P. Mankame at Atria Institute of Technology. It provides details about the course including semester, credits, teaching hours and evaluation criteria. It also includes information about the institute's vision, mission and program educational objectives for the Master of Computer Applications program. The document outlines some key topics that will be covered in the course like introduction to data communication, network types, topologies and protocols.

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Dr. Dattatreya P. Mankame Professor and HOD, Dept. of MCA, Atria Institute of Technology, Hebbal, Bengaluru Dr.Dattatreya P. Mankame
Computer Networks  Semester : 1  Sub-Code: 22MCA14  CIE Marks : 50  SEE Marks : 50  Exam Hours : 03  Credits : 03  Teaching Hours (L:T:P) : 3:0:0  Scheme : 2022  Academic Year : 2022-23 Atria Institute of Technology, Bengaluru Department of MCA Dr.Dattatreya P. Mankame Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
AIT-MCA-Vision To be a leading knowledge center for imparting quality education in computer applications, inter-disciplinary research and develop competent professionals to serve the society. AIT-MCA Mission Department of Master of Computer Applications (MCA) committed to – M1: Empower graduates with knowledge, skills and attitude to develop highly competent professionals. M2: Interdisciplinary projects, internships and value added training programs in cutting edge technologies. M3: Collaborate with academia and industry for research, consultancy and encouraging entrepreneurship. M4: Develop competent professionals with social and ethical values to serve the society. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
AIT-MCA-PEOs Professionals from the Master of Computer Applications (MCA) should: PEO1: Develop the ability to plan, analyse, design, implement and maintain the software products for real life applications. PEO2: Practice effectively as individuals and as team members in multidisciplinary projects by inculcating professional skills, ethical behaviour, and leadership qualities. PEO3: Develop lifelong learning capabilities to set up their own enterprise in various sectors of computer applications and be able to pursue higher studies. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
1. Resource sharing such as printers and storage devices 2. Exchange of information by means of e-Mails and FTP 3. Information sharing by using Web or Internet 4. Interaction with other users using dynamic web pages 5. Audio/Video conferences 6. Instant messaging 7. e-commerce 8. On-line examination / Interviews 9. e-papers Applications of Communication & Computer Network Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Module 1 INTRODUCTION Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Text Book: Ch:1 and Ch:2
Introduction  The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data.  Communication means sharing of information between two devices using some medium such as wire cable (LAN), internet.  Data communication means exchange of data between two devices via some form of transmission medium such as a wire cable.  Information sharing can be of two types .  Local Communication : Face to face  Remote Communication : Takes place over a distance.  Networking: Two or more devices connected by some communication link. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Characteristics of data communication system  Delivery : The system must deliver data to the correct destination .  Accuracy :The system must deliver the data accurately.  Timeliness: The system must deliver data in a timely manner. Real time transmission : Delivering data as they are produced, in the same order that they are produced, and without significant delay.  Jitter: Jitter refers to variation in the packet arrival time.  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. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Components of data communication  Message : The message is the information (data) to be communicated.  Sender: The sender is the device that sends the data message.  Receiver: The receiver is the device that receives the message.  Transmission medium: The transmission medium is the physical path by which a message travels from sender to receiver.  Protocol: A protocol is a set of rules that govern data communications. Without a protocol, two devices may be connected but not communicating. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Data Representation  Text: It is represented as a bit pattern, a sequence of bits(0s or 1s). Each set is called a code, and the process of representing symbols is called coding.  Numbers: It is also represented by bit patterns .  Images: An image is composed of a matrix of pixels where each pixel is a small dot . After an image is divided into pixels, each pixel is assigned a bit pattern.  Audio: It refers to the recording or broadcasting of sound or music. It is continuous, not discrete.  Video: Video refers to the recording or broadcasting of a picture or movie. It can be continuous or discrete. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Data Flow  Communication between two devices can be simplex, half-duplex, or full-duplex as shown in figure. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Data Flow  Simplex: Communication is unidirectional, Only one of the two devices on a link can transmit; the other can only receive. E.g. : One way street, Keyboard , Monitor.  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. E.g.: Walkie Talkie.  Full duplex: Both stations can transmit and receive simultaneously. It is like a two way street with the traffic flowing in both the directions at the same time. E.g .: Telephone network Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Networks  Networks: A network is a set of devices (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.  Distributed Processing : Here task is divided among multiple computers. Instead of one single large machine being responsible for all aspects of a process, separate computers handle a subset. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Network Criteria  Performance : It can be measured in two ways.  Transit time: It is the amount of time required for a message to travel from one device to another.  Response time: It is the time elapsed between an inquiry and a response.  Reliability : It is measured by the frequency of failure, the time it takes a link to recover from failure.  Security : It includes protecting data from unauthorized access, protecting data from damage, implementing policies and procedures for recovery from data losses. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Physical Structures- Type of Connection  Point to Point :  It provides a dedicated link between two devices .  The entire capacity of the link is reserved for transmission between those two devices.  It uses an actual length of wire or cable to connect the two ends.  Multi Point :  More than twospecific deviceshare a single link.  Capacity of the channel is either spatially or temporally shared.  Spatially shared: Several devices can use the link simultaneously.  Temporally shared : Users take turns. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Physical Structures- Type of Connection Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Physical Topology  Two or more devices connect to a link; two or more links form a topology.  Topology : It is the geometric representation of relationship of all the links and linking devices to one another.  Four basic topologies : Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Mesh Topology  Every device has a dedicated point-to-point link to every other device.  The term dedicated means that the link carries traffic only between the two devices it connects.  To find the number of physical links in a fully connected mesh network with n nodes, n(n - 1) / 2 duplex mode links A fully connected mesh topology Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Mesh Topology Advantages : • A mesh topology is robust. If one link becomes unusable, it does not incapacitate the entire system. • Point-to-point links make fault identification and fault isolation easy. • Privacy or security : When every message travels along a dedicated line, only the intended recipient sees it. Disadvantages : • Installation and reconnection are difficult. • The hardware required to connect each link can be prohibitively expensive. • The sheer bulk of the wiring can be greater than the available space can accommodate. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Star Topology  Each device has a dedicated point-to-point link only to a central controller, usually called a hub.  The controller acts as an exchange: • If one device wants to send data to another, it sends the data to the controller, which then relays the data to the other connected device. A star topology connecting 4 stations Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Star Topology Advantages : • Less expensive than a mesh topology. Each device needs only one link and one I/O port to connect it to any number of others. • Easy to install and reconfigure. • Requires less cabling than mesh topology. • Robustness: If one link fails, only that link is affected. All other links remain active. As a result fault identification and fault isolation becomes easy. Disadvantages : • Dependency of whole topology on one single point, the hub. E.g. LAN Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Bus Topology  One long cable acts as a backbone to link all the devices in a network.  Nodes are connected to the bus cable by drop lines and taps.  A drop line is a connection running between the device and the main cable.  As a signal travels along the back bone, some of its energy is transformed into heat.  As a result there is a limit on the number of taps a bus can support and on the distance between those taps. A bus topology connecting three stations Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Bus Topology Advantages : • Ease of installation : Backbone cable can be laid along the most efficient path, then connected to the nodes and drop lines. • Signal reflection at the taps can cause degradation in quality. This degradation can be controlled by limiting the number and spacing of devices connected to a given length of cable. • Adding new devices may therefore require modification or replacement of the backbone. • Redundancy is eliminated : Only the backbone cable stretches through the entire facility. Disadvantages : • A bus is usually designed to be optimally efficient at installation. It can therefore be difficult to add new devices. • A fault or break in the bus cable stops all transmission, and the damaged area reflects signals back in the direction of origin, creating noise in both directions. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Ring Topology  Each device has a 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 device in the ring incorporates a repeater.  When a device receives a signal intended for another device , its repeater regenerates the bits and passes them along. A ring topology connecting six stations Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Ring Topology Advantages : • A ring is relatively easy to install and reconfigure. Each device is linked to only its immediate neighbors. • To add or delete a device requires changing only two connections. • Fault isolation is simplified. Here, a signal is circulating at all times. If one device does not receive a signal within a specified period, it can issue an alarm. • The alarm alerts the network operator to the problem and its location. Disadvantages : • Unidirectional traffic can be a disadvantage. In a simple ring, a break in the ring can disable the entire network. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Hybrid Topology A hybrid topology: a star backbone with three bus networks Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Network Models  Local Area Networks (LAN): It isprivately owned and links the devices in a single office, building, or campus. • LAN can be as simple as two PCs and a printer in someone's home office . Its size is limited to a few kilometers. • LANs are designed to allow resources to be shared between personal computers or workstations. • The resources to be shared can include hardware (e.g., a printer), software (e.g., an application program). An isolated LAN connecting 12 computers to a hub in a closet Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Network Models  Wide Area Networks (WAN): • It provides long-distance transmission of data, image, audio, and video information over large geographic areas that comprise a country, a continent or even the whole world. • Two types of WAN:  Point to Point WAN : It is a line leased from a telephone that connects a home computer or a small LAN to an Internet service provider (ISP).  The switched WAN : It connects the end systems, which usually comprise a router that connects to another LAN or WAN. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Network Models  Wide Area Networks (WAN): WANs: a switched WAN and a point-to-point WAN Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Internetwork A heterogeneous network made of four WANs and two LANs Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
The Internet  Difference between internet and Internet  History: Mid 1960s - ARPA Project – by DoD  1967, ARPA with ACM (Association for Computing Machinery) – attach each host computer with IMP (interface Message Processor) 1969, ARPAnet with four nodes using Network Control Protocol (NCP) software 1972, Paper on TCP/IP published and implemented Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
The Internet Network Access Point (NAP) Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Protocols and Standards  A protocol is a set of rules that govern data communications. A protocol defines what is communicated, how it is communicated, and when it is communicated.  The key elements of a protocol are syntax, semantics, and timing. Syntax. The term syntax refers to the structure or format of the data, meaning the order in which they are presented. Semantics. The word semantics refers to the meaning of each section of bits Timing. The term timing refers to two characteristics: when data should be sent and how fast they can be sent. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Standards and Administration  Standards are essential in creating and maintaining an open and competitive market for equipment manufacturers and in guaranteeing national and international interoperability of data and telecommunications technology and processes  Data communication standards fall into two categories: de facto (meaning "by fact" or "by convention") and de jure (meaning "by law" or "by regulation").  De facto. Standards that have not been approved by an organized body but have been adopted as standards through widespread use are de facto standards.  De jure. Those standards that have been legislated by an officially recognized body are de jure standards Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Standards Organizations  Standards are developed through the cooperation of standards creation committees, forums, and government regulatory agencies  International Organization for Standardization (ISO)  International Telecommunication Union-Telecommunication Standards Sector (ITU-T)  American National Standards Institute (ANSI)  Electronic Industries Association (EIA)  Institute of Electrical and Electronics Engineers (IEEE) Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Internet Standards  Internet Standard : It is a formalized regulation that must be followed and useful to those who work with the internet.  A specification begins as an Internet draft. An Internet draft is a working document with no official status (a work in progress) and a six month life time.  This draft is published as a Request for comment(RFC) where each RFC is edited , assigned a number and made available to all interested parties. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Maturity Levels  Proposed standard : It is a specification which is stable, understood and of sufficient interest to the Internet community.  Draft standard : A proposed standard is elevated to draft standard status after at least two successful independent and interoperable implementations.  Internet standard : A draft standard reaches internet standard after demonstrations of successful implementation.  Historic : They have never passed the necessary maturity levels to become an internet standard.  Experimental : It describes work related to an experimental operation that does not affect the operation of the internet.  Informational : It contains general, historical or tutorial information related to the internet . Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Network Models PROTOCOL LAYERING  Protocol defines the rules that both the sender and receiver and all intermediate devices need to follow to be able to communicate effectively.  When communication is simple- one simple protocol  When the communication is complex-need to divide the task between different layers, in which case we need a protocol at each layer, or protocol layering. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Scenarios  Two simple scenarios to understand the need for protocol layering. First scenario  communication is so simple that it can occur in only one layer.  Assume Maria and Ann are neighbors with a lot of common ideas.  Communication between Maria and Ann takes place in one layer, face to face, in the same language, shown in Fig2.1. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
2.42  Set of rules needs to be followed for Scenario. 1. Both should greet each other when they meet. 2. They should confine their vocabulary to the level of their friendship. 3. Each party knows that she should refrain from speaking when the other party is speaking. 4. Each party knows that the conversation should be a dialog, not a monolog: both should have the opportunity to talk about the issue. 5. They should exchange some nice words when they leave. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Second Scenario  Assume that Ann is offered a higher-level position in her company, but needs to move to another branch located in a city very far from Maria.  The two friends still want to continue their communication and exchange ideas because they have come up with an innovative project to start a new business when they both retire.  They decided to communicate using regular mail through the post office.  To protect their ideas both agreed on an encryption/decryption technique. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
 The sender of the letter encrypts, while the receiver of the letter decrypts it to get the original letter.  Thus, communication between parties takes place in three layers, as shown in Figure 2.2. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
 Assumption: Maria sends the first letter to Ann. @ Maria’s side: • Maria talks to the machine at the third layer as though the machine is Ann and is listening to her. • The third layer machine listens to what Maria says and creates the plaintext (a letter in English) and passes to the second layer machine. • The second layer machine takes the plaintext, encrypts it, and creates the ciphertext and passes to the first layer machine. • The first layer machine, presumably a robot, takes the ciphertext, puts it in an envelope, adds the sender and receiver addresses, and mails it. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
@ Ann’s side: • The first layer machine picks up the letter from Ann’s mail box, recognizing the letter from Maria by the sender address. • The machine takes out the ciphertext from the envelope and delivers it to the second layer machine. • The second layer machine decrypts the message, creates the plaintext, and passes to the third-layer machine. • The third layer machine takes the plaintext and reads it as though Maria is speaking.  Protocol layering enables us to divide a complex task into several smaller and simpler tasks. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. THE OSI MODEL Layered Architecture Peer-to-Peer Processes Encapsulation Topics discussed in this section: Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. THE OSI MODEL Layered Architecture Peer-to-Peer Processes Encapsulation Topics discussed in this section: ISO is the organization. OSI is the model. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Layered architecture: Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Physical Layer • The physical layer coordinates the functions required to carry a bit stream over a physical medium. • It deals with the mechanical and electrical specifications of the interface and transmission medium. • It also defines the procedures and functions that physical devices and interfaces have to perform for transmission to occur Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
The physical layer is also concerned with the following: o Physical characteristics of interfaces and medium. o Representation of bits. The physical layer data consists of a stream of bits (sequence of Os or 1s) with no interpretation. To be transmitted, bits must be encoded into signals--electrical or optical. The physical layer defines the type of encoding (how Os and Is are changed to signals). o Data rate. The transmission rate-the number of bits sent each second o Synchronization of bits. The sender and receiver not only must use the same bit rate but also must be synchronized at the bit level. o Line configuration. The physical layer is concerned with the connection of devices to the media. i.e. in a point-to-point configuration, or In a multipoint configuration o Physical topology. The physical topology defines how devices are connected to make a network. o Transmission mode. The physical layer also defines the direction of transmission between two devices: simplex, half-duplex, or full-duplex. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Data link Layer • The data link layer transforms the physical layer, a raw transmission facility, to a reliable link. • It makes the physical layer appear error-free to the upper layer (network layer). • Figure 2.6 shows the relationship of the data link layer to the network and physical layers Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
The Data link layer is also concerned with the following: • Framing: The data link layer divides the stream of bits received from the network layer into manageable data units called frames. • Physical addressing. If frames are to be distributed to different systems on the network, the data link layer adds a header to the frame to define the sender and/or receiver of the frame. If the frame is intended for a system outside the sender's network, the receiver address is the address of the device that connects the network to the next one. • Flow control. If the rate at which the data are absorbed by the receiver is less than the rate at which data are produced in the sender, the data link layer imposes a flow control mechanism to avoid overwhelming the receiver. • Error control. The data link layer adds reliability to the physical layer by adding mechanisms to detect and retransmit damaged or lost frames. It also uses a mechanism to recognize duplicate frames. Error control is normally achieved through a trailer added to the end of the frame. • Access control. When two or more devices are connected to the same link, data link layer protocols are necessary to determine which device has control over the link at any given time. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Network Layer • The network layer is responsible for the source-to- destination delivery of a packet, possibly across multiple networks (links). Whereas the data link layer oversees the delivery of the packet between two systems on the same network (links), the network layer ensures that each packet gets from its point of origin to its final destination Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
The Network layer is also concerned with the following: • Logical addressing. The physical addressing implemented by the data link layer handles the addressing problem locally. If a packet passes the network boundary, we need another addressing system to help distinguish the source and destination systems. The network layer adds a header to the packet coming from the upper layer that, among other things, includes the logical addresses of the sender and receiver. We discuss logical addresses later in this chapter. • Routing. When independent networks or links are connected to create internetworks (network of networks) or a large network, the connecting devices (called routers or switches) route or switch the packets to their final destination. One of the functions of the network layer is to provide this mechanism. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Transport Layer • The transport layer is responsible for process-to-process delivery of the entire message. A process is an application program running on a host. Whereas the network layer oversees source-to-destination delivery of individual packets, it does not recognize any relationship between those packets. It treats each one independently, as though each piece belonged to a separate message, whether or not it does. • The transport layer, on the other hand, ensures that the whole message arrives intact and in order, overseeing both error control and flow control at the source-to-destination level. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
The Transport layer is also concerned with the following: • Service-point addressing. Source-to-destination delivery means delivery not only from one computer to the next but also from a specific process (running program) on one computer to a specific process (running program) on the other. The transport layer header must therefore include a type of address called a service-point address (or port address). The network layer gets each packet to the correct computer; the transport layer gets the entire message to the correct process on that computer. • Segmentation and reassembly. A message is divided into transmittable segments, with each segment containing a sequence number. These numbers enable the transport layer to reassemble the message correctly upon arriving at the destination and to identify and replace packets that were lost in transmission. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
• Connection control. The transport layer can be either connectionless or connection oriented. A connectionless transport layer treats each segment as an independent packet and delivers it to the transport layer at the destination machine. A connection oriented transport layer makes a connection with the transport layer at the destination machine first before delivering the packets. After all the data are transferred, the connection is terminated. • Flow control. Like the data link layer, the transport layer is responsible for flow control. However, flow control at this layer is performed end to end rather than across a single link. • Error control. Like the data link layer, the transport layer is responsible for error control. However, error control at this layer is performed process-to-process rather than across a single link. The sending transport layer makes sure that the entire message arrives at the receiving transport layer without error (damage, loss, or duplication). Error correction is usually achieved through retransmission Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Session Layer • The services provided by the first three layers (physical, data link, and network) are not sufficient for some processes. • The session layer is the network dialog controller. • It establishes, maintains, and synchronizes the interaction among communicating system
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Specific responsibilities of the session layer include the following: o Dialog control. The session layer allows two systems to enter into a dialog. It allows the communication between two processes to take place in either halfduplex (one way at a time) or full-duplex (two ways at a time) mode. o Synchronization. The session layer allows a process to add checkpoints, or synchronization points, to a stream of data. For example, if a system is sending a file of 2000 pages, it is advisable to insert checkpoints after every 100 pages to ensure that each 100-page unit is received and acknowledged independently. In this case, if a crash happens during the transmission of page 523, the only pages that need to be resent after system recovery are pages 501 to 523. Pages previous to 501 need not be resent.
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Presentation Layer • The presentation layer is concerned with the syntax and semantics of the information exchanged between two systems. • Figure 2.13 shows the relationship between the presentation layer and the application and session layers.
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Specific responsibilities of the presentation layer include the following: o Translation. The processes (running programs) in two systems are usually exchanging information in the form of character strings, numbers, and so on. The information must be changed to bit streams before being transmitted. Because different computers use different encoding systems, the presentation layer is responsible for interoperability between these different encoding methods. The presentation layer at the sender changes the information from its sender-dependent format into a common format. The presentation layer at the receiving machine changes the common format into its receiver- dependent format. o Encryption. To carry sensitive information, a system must be able to ensure privacy. Encryption means that the sender transforms the original information to another form and sends the resulting message out over the network. Decryption reverses the original process to transform the message back to its original form. oCompression. Data compression reduces the number of bits contained in the information. Data compression becomes particularly important in the transmission of multimedia such as text, audio, and video
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Application Layer • The application layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as electronic mail, remote file access and transfer, shared database management, and other types of distributed information services.
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Specific services provided by the application layer include the following: o Network virtual terminal. A network virtual terminal is a software version of a physical terminal, and it allows a user to log on to a remote host. To do so, the application creates a software emulation of a terminal at the remote host. The user's computer talks to the software terminal which, in turn, talks to the host, and vice versa. The remote host believes it is communicating with one of its own terminals and allows the user to log on o File transfer, access, and management. This application allows a user to access files in a remote host (to make changes or read data), to retrieve files from a remote computer for use in the local computer, and to manage or control files in a remote computer locally. o Mail services. This application provides the basis for e-mail forwarding and storage. o Directory services. This application provides distributed database sources and access for global information about various objects and services.
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT

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22MCA14_AIT_DPM_M1.pptx

  • 1.
    Dr. Dattatreya P.Mankame Professor and HOD, Dept. of MCA, Atria Institute of Technology, Hebbal, Bengaluru Dr.Dattatreya P. Mankame
  • 2.
    Computer Networks  Semester: 1  Sub-Code: 22MCA14  CIE Marks : 50  SEE Marks : 50  Exam Hours : 03  Credits : 03  Teaching Hours (L:T:P) : 3:0:0  Scheme : 2022  Academic Year : 2022-23 Atria Institute of Technology, Bengaluru Department of MCA Dr.Dattatreya P. Mankame Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 3.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 4.
  • 5.
  • 6.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 7.
    AIT-MCA-Vision To be aleading knowledge center for imparting quality education in computer applications, inter-disciplinary research and develop competent professionals to serve the society. AIT-MCA Mission Department of Master of Computer Applications (MCA) committed to – M1: Empower graduates with knowledge, skills and attitude to develop highly competent professionals. M2: Interdisciplinary projects, internships and value added training programs in cutting edge technologies. M3: Collaborate with academia and industry for research, consultancy and encouraging entrepreneurship. M4: Develop competent professionals with social and ethical values to serve the society. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 8.
    AIT-MCA-PEOs Professionals from theMaster of Computer Applications (MCA) should: PEO1: Develop the ability to plan, analyse, design, implement and maintain the software products for real life applications. PEO2: Practice effectively as individuals and as team members in multidisciplinary projects by inculcating professional skills, ethical behaviour, and leadership qualities. PEO3: Develop lifelong learning capabilities to set up their own enterprise in various sectors of computer applications and be able to pursue higher studies. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 9.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 10.
    1. Resource sharingsuch as printers and storage devices 2. Exchange of information by means of e-Mails and FTP 3. Information sharing by using Web or Internet 4. Interaction with other users using dynamic web pages 5. Audio/Video conferences 6. Instant messaging 7. e-commerce 8. On-line examination / Interviews 9. e-papers Applications of Communication & Computer Network Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 11.
    Module 1 INTRODUCTION AtriaInstitute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Text Book: Ch:1 and Ch:2
  • 12.
    Introduction  The worddata refers to information presented in whatever form is agreed upon by the parties creating and using the data.  Communication means sharing of information between two devices using some medium such as wire cable (LAN), internet.  Data communication means exchange of data between two devices via some form of transmission medium such as a wire cable.  Information sharing can be of two types .  Local Communication : Face to face  Remote Communication : Takes place over a distance.  Networking: Two or more devices connected by some communication link. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 13.
    Characteristics of datacommunication system  Delivery : The system must deliver data to the correct destination .  Accuracy :The system must deliver the data accurately.  Timeliness: The system must deliver data in a timely manner. Real time transmission : Delivering data as they are produced, in the same order that they are produced, and without significant delay.  Jitter: Jitter refers to variation in the packet arrival time.  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. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 14.
    Components of datacommunication  Message : The message is the information (data) to be communicated.  Sender: The sender is the device that sends the data message.  Receiver: The receiver is the device that receives the message.  Transmission medium: The transmission medium is the physical path by which a message travels from sender to receiver.  Protocol: A protocol is a set of rules that govern data communications. Without a protocol, two devices may be connected but not communicating. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 15.
    Data Representation  Text:It is represented as a bit pattern, a sequence of bits(0s or 1s). Each set is called a code, and the process of representing symbols is called coding.  Numbers: It is also represented by bit patterns .  Images: An image is composed of a matrix of pixels where each pixel is a small dot . After an image is divided into pixels, each pixel is assigned a bit pattern.  Audio: It refers to the recording or broadcasting of sound or music. It is continuous, not discrete.  Video: Video refers to the recording or broadcasting of a picture or movie. It can be continuous or discrete. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 16.
    Data Flow  Communicationbetween two devices can be simplex, half-duplex, or full-duplex as shown in figure. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 17.
    Data Flow  Simplex:Communication is unidirectional, Only one of the two devices on a link can transmit; the other can only receive. E.g. : One way street, Keyboard , Monitor.  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. E.g.: Walkie Talkie.  Full duplex: Both stations can transmit and receive simultaneously. It is like a two way street with the traffic flowing in both the directions at the same time. E.g .: Telephone network Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 18.
    Networks  Networks: Anetwork is a set of devices (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.  Distributed Processing : Here task is divided among multiple computers. Instead of one single large machine being responsible for all aspects of a process, separate computers handle a subset. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 19.
    Network Criteria  Performance: It can be measured in two ways.  Transit time: It is the amount of time required for a message to travel from one device to another.  Response time: It is the time elapsed between an inquiry and a response.  Reliability : It is measured by the frequency of failure, the time it takes a link to recover from failure.  Security : It includes protecting data from unauthorized access, protecting data from damage, implementing policies and procedures for recovery from data losses. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 20.
    Physical Structures- Typeof Connection  Point to Point :  It provides a dedicated link between two devices .  The entire capacity of the link is reserved for transmission between those two devices.  It uses an actual length of wire or cable to connect the two ends.  Multi Point :  More than twospecific deviceshare a single link.  Capacity of the channel is either spatially or temporally shared.  Spatially shared: Several devices can use the link simultaneously.  Temporally shared : Users take turns. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 21.
    Physical Structures- Typeof Connection Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 22.
    Physical Topology  Twoor more devices connect to a link; two or more links form a topology.  Topology : It is the geometric representation of relationship of all the links and linking devices to one another.  Four basic topologies : Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 23.
    Mesh Topology  Everydevice has a dedicated point-to-point link to every other device.  The term dedicated means that the link carries traffic only between the two devices it connects.  To find the number of physical links in a fully connected mesh network with n nodes, n(n - 1) / 2 duplex mode links A fully connected mesh topology Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 24.
    Mesh Topology Advantages : •A mesh topology is robust. If one link becomes unusable, it does not incapacitate the entire system. • Point-to-point links make fault identification and fault isolation easy. • Privacy or security : When every message travels along a dedicated line, only the intended recipient sees it. Disadvantages : • Installation and reconnection are difficult. • The hardware required to connect each link can be prohibitively expensive. • The sheer bulk of the wiring can be greater than the available space can accommodate. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 25.
    Star Topology  Eachdevice has a dedicated point-to-point link only to a central controller, usually called a hub.  The controller acts as an exchange: • If one device wants to send data to another, it sends the data to the controller, which then relays the data to the other connected device. A star topology connecting 4 stations Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 26.
    Star Topology Advantages : •Less expensive than a mesh topology. Each device needs only one link and one I/O port to connect it to any number of others. • Easy to install and reconfigure. • Requires less cabling than mesh topology. • Robustness: If one link fails, only that link is affected. All other links remain active. As a result fault identification and fault isolation becomes easy. Disadvantages : • Dependency of whole topology on one single point, the hub. E.g. LAN Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 27.
    Bus Topology  Onelong cable acts as a backbone to link all the devices in a network.  Nodes are connected to the bus cable by drop lines and taps.  A drop line is a connection running between the device and the main cable.  As a signal travels along the back bone, some of its energy is transformed into heat.  As a result there is a limit on the number of taps a bus can support and on the distance between those taps. A bus topology connecting three stations Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 28.
    Bus Topology Advantages : •Ease of installation : Backbone cable can be laid along the most efficient path, then connected to the nodes and drop lines. • Signal reflection at the taps can cause degradation in quality. This degradation can be controlled by limiting the number and spacing of devices connected to a given length of cable. • Adding new devices may therefore require modification or replacement of the backbone. • Redundancy is eliminated : Only the backbone cable stretches through the entire facility. Disadvantages : • A bus is usually designed to be optimally efficient at installation. It can therefore be difficult to add new devices. • A fault or break in the bus cable stops all transmission, and the damaged area reflects signals back in the direction of origin, creating noise in both directions. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 29.
    Ring Topology  Eachdevice has a 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 device in the ring incorporates a repeater.  When a device receives a signal intended for another device , its repeater regenerates the bits and passes them along. A ring topology connecting six stations Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 30.
    Ring Topology Advantages : •A ring is relatively easy to install and reconfigure. Each device is linked to only its immediate neighbors. • To add or delete a device requires changing only two connections. • Fault isolation is simplified. Here, a signal is circulating at all times. If one device does not receive a signal within a specified period, it can issue an alarm. • The alarm alerts the network operator to the problem and its location. Disadvantages : • Unidirectional traffic can be a disadvantage. In a simple ring, a break in the ring can disable the entire network. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 31.
    Hybrid Topology A hybridtopology: a star backbone with three bus networks Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 32.
    Network Models  LocalArea Networks (LAN): It isprivately owned and links the devices in a single office, building, or campus. • LAN can be as simple as two PCs and a printer in someone's home office . Its size is limited to a few kilometers. • LANs are designed to allow resources to be shared between personal computers or workstations. • The resources to be shared can include hardware (e.g., a printer), software (e.g., an application program). An isolated LAN connecting 12 computers to a hub in a closet Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 33.
    Network Models  WideArea Networks (WAN): • It provides long-distance transmission of data, image, audio, and video information over large geographic areas that comprise a country, a continent or even the whole world. • Two types of WAN:  Point to Point WAN : It is a line leased from a telephone that connects a home computer or a small LAN to an Internet service provider (ISP).  The switched WAN : It connects the end systems, which usually comprise a router that connects to another LAN or WAN. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 34.
    Network Models  WideArea Networks (WAN): WANs: a switched WAN and a point-to-point WAN Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 35.
    Internetwork A heterogeneous networkmade of four WANs and two LANs Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 36.
    The Internet  Differencebetween internet and Internet  History: Mid 1960s - ARPA Project – by DoD  1967, ARPA with ACM (Association for Computing Machinery) – attach each host computer with IMP (interface Message Processor) 1969, ARPAnet with four nodes using Network Control Protocol (NCP) software 1972, Paper on TCP/IP published and implemented Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 37.
    The Internet Network AccessPoint (NAP) Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 38.
    Protocols and Standards A protocol is a set of rules that govern data communications. A protocol defines what is communicated, how it is communicated, and when it is communicated.  The key elements of a protocol are syntax, semantics, and timing. Syntax. The term syntax refers to the structure or format of the data, meaning the order in which they are presented. Semantics. The word semantics refers to the meaning of each section of bits Timing. The term timing refers to two characteristics: when data should be sent and how fast they can be sent. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 39.
    Standards and Administration Standards are essential in creating and maintaining an open and competitive market for equipment manufacturers and in guaranteeing national and international interoperability of data and telecommunications technology and processes  Data communication standards fall into two categories: de facto (meaning "by fact" or "by convention") and de jure (meaning "by law" or "by regulation").  De facto. Standards that have not been approved by an organized body but have been adopted as standards through widespread use are de facto standards.  De jure. Those standards that have been legislated by an officially recognized body are de jure standards Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 40.
    Standards Organizations  Standardsare developed through the cooperation of standards creation committees, forums, and government regulatory agencies  International Organization for Standardization (ISO)  International Telecommunication Union-Telecommunication Standards Sector (ITU-T)  American National Standards Institute (ANSI)  Electronic Industries Association (EIA)  Institute of Electrical and Electronics Engineers (IEEE) Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 41.
    Internet Standards  InternetStandard : It is a formalized regulation that must be followed and useful to those who work with the internet.  A specification begins as an Internet draft. An Internet draft is a working document with no official status (a work in progress) and a six month life time.  This draft is published as a Request for comment(RFC) where each RFC is edited , assigned a number and made available to all interested parties. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 42.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 43.
    Maturity Levels  Proposedstandard : It is a specification which is stable, understood and of sufficient interest to the Internet community.  Draft standard : A proposed standard is elevated to draft standard status after at least two successful independent and interoperable implementations.  Internet standard : A draft standard reaches internet standard after demonstrations of successful implementation.  Historic : They have never passed the necessary maturity levels to become an internet standard.  Experimental : It describes work related to an experimental operation that does not affect the operation of the internet.  Informational : It contains general, historical or tutorial information related to the internet . Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 44.
    Network Models PROTOCOL LAYERING Protocol defines the rules that both the sender and receiver and all intermediate devices need to follow to be able to communicate effectively.  When communication is simple- one simple protocol  When the communication is complex-need to divide the task between different layers, in which case we need a protocol at each layer, or protocol layering. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 45.
    Scenarios  Two simplescenarios to understand the need for protocol layering. First scenario  communication is so simple that it can occur in only one layer.  Assume Maria and Ann are neighbors with a lot of common ideas.  Communication between Maria and Ann takes place in one layer, face to face, in the same language, shown in Fig2.1. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 46.
    2.42  Set ofrules needs to be followed for Scenario. 1. Both should greet each other when they meet. 2. They should confine their vocabulary to the level of their friendship. 3. Each party knows that she should refrain from speaking when the other party is speaking. 4. Each party knows that the conversation should be a dialog, not a monolog: both should have the opportunity to talk about the issue. 5. They should exchange some nice words when they leave. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 47.
    Second Scenario  Assumethat Ann is offered a higher-level position in her company, but needs to move to another branch located in a city very far from Maria.  The two friends still want to continue their communication and exchange ideas because they have come up with an innovative project to start a new business when they both retire.  They decided to communicate using regular mail through the post office.  To protect their ideas both agreed on an encryption/decryption technique. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 48.
     The senderof the letter encrypts, while the receiver of the letter decrypts it to get the original letter.  Thus, communication between parties takes place in three layers, as shown in Figure 2.2. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 49.
     Assumption: Mariasends the first letter to Ann. @ Maria’s side: • Maria talks to the machine at the third layer as though the machine is Ann and is listening to her. • The third layer machine listens to what Maria says and creates the plaintext (a letter in English) and passes to the second layer machine. • The second layer machine takes the plaintext, encrypts it, and creates the ciphertext and passes to the first layer machine. • The first layer machine, presumably a robot, takes the ciphertext, puts it in an envelope, adds the sender and receiver addresses, and mails it. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 50.
    @ Ann’s side: •The first layer machine picks up the letter from Ann’s mail box, recognizing the letter from Maria by the sender address. • The machine takes out the ciphertext from the envelope and delivers it to the second layer machine. • The second layer machine decrypts the message, creates the plaintext, and passes to the third-layer machine. • The third layer machine takes the plaintext and reads it as though Maria is speaking.  Protocol layering enables us to divide a complex task into several smaller and simpler tasks. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 51.
    Established in 1947,the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. THE OSI MODEL Layered Architecture Peer-to-Peer Processes Encapsulation Topics discussed in this section: Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 52.
    Established in 1947,the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. THE OSI MODEL Layered Architecture Peer-to-Peer Processes Encapsulation Topics discussed in this section: ISO is the organization. OSI is the model. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 53.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 54.
    Layered architecture: Atria Instituteof Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 55.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 56.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 57.
    Physical Layer • Thephysical layer coordinates the functions required to carry a bit stream over a physical medium. • It deals with the mechanical and electrical specifications of the interface and transmission medium. • It also defines the procedures and functions that physical devices and interfaces have to perform for transmission to occur Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 58.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 59.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 60.
    The physical layeris also concerned with the following: o Physical characteristics of interfaces and medium. o Representation of bits. The physical layer data consists of a stream of bits (sequence of Os or 1s) with no interpretation. To be transmitted, bits must be encoded into signals--electrical or optical. The physical layer defines the type of encoding (how Os and Is are changed to signals). o Data rate. The transmission rate-the number of bits sent each second o Synchronization of bits. The sender and receiver not only must use the same bit rate but also must be synchronized at the bit level. o Line configuration. The physical layer is concerned with the connection of devices to the media. i.e. in a point-to-point configuration, or In a multipoint configuration o Physical topology. The physical topology defines how devices are connected to make a network. o Transmission mode. The physical layer also defines the direction of transmission between two devices: simplex, half-duplex, or full-duplex. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 61.
    Data link Layer •The data link layer transforms the physical layer, a raw transmission facility, to a reliable link. • It makes the physical layer appear error-free to the upper layer (network layer). • Figure 2.6 shows the relationship of the data link layer to the network and physical layers Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 64.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 65.
    The Data linklayer is also concerned with the following: • Framing: The data link layer divides the stream of bits received from the network layer into manageable data units called frames. • Physical addressing. If frames are to be distributed to different systems on the network, the data link layer adds a header to the frame to define the sender and/or receiver of the frame. If the frame is intended for a system outside the sender's network, the receiver address is the address of the device that connects the network to the next one. • Flow control. If the rate at which the data are absorbed by the receiver is less than the rate at which data are produced in the sender, the data link layer imposes a flow control mechanism to avoid overwhelming the receiver. • Error control. The data link layer adds reliability to the physical layer by adding mechanisms to detect and retransmit damaged or lost frames. It also uses a mechanism to recognize duplicate frames. Error control is normally achieved through a trailer added to the end of the frame. • Access control. When two or more devices are connected to the same link, data link layer protocols are necessary to determine which device has control over the link at any given time. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 66.
    Network Layer • Thenetwork layer is responsible for the source-to- destination delivery of a packet, possibly across multiple networks (links). Whereas the data link layer oversees the delivery of the packet between two systems on the same network (links), the network layer ensures that each packet gets from its point of origin to its final destination Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 67.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 70.
    The Network layeris also concerned with the following: • Logical addressing. The physical addressing implemented by the data link layer handles the addressing problem locally. If a packet passes the network boundary, we need another addressing system to help distinguish the source and destination systems. The network layer adds a header to the packet coming from the upper layer that, among other things, includes the logical addresses of the sender and receiver. We discuss logical addresses later in this chapter. • Routing. When independent networks or links are connected to create internetworks (network of networks) or a large network, the connecting devices (called routers or switches) route or switch the packets to their final destination. One of the functions of the network layer is to provide this mechanism. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 71.
    Transport Layer • Thetransport layer is responsible for process-to-process delivery of the entire message. A process is an application program running on a host. Whereas the network layer oversees source-to-destination delivery of individual packets, it does not recognize any relationship between those packets. It treats each one independently, as though each piece belonged to a separate message, whether or not it does. • The transport layer, on the other hand, ensures that the whole message arrives intact and in order, overseeing both error control and flow control at the source-to-destination level. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 72.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 74.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 75.
    The Transport layeris also concerned with the following: • Service-point addressing. Source-to-destination delivery means delivery not only from one computer to the next but also from a specific process (running program) on one computer to a specific process (running program) on the other. The transport layer header must therefore include a type of address called a service-point address (or port address). The network layer gets each packet to the correct computer; the transport layer gets the entire message to the correct process on that computer. • Segmentation and reassembly. A message is divided into transmittable segments, with each segment containing a sequence number. These numbers enable the transport layer to reassemble the message correctly upon arriving at the destination and to identify and replace packets that were lost in transmission. Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 76.
    • Connection control.The transport layer can be either connectionless or connection oriented. A connectionless transport layer treats each segment as an independent packet and delivers it to the transport layer at the destination machine. A connection oriented transport layer makes a connection with the transport layer at the destination machine first before delivering the packets. After all the data are transferred, the connection is terminated. • Flow control. Like the data link layer, the transport layer is responsible for flow control. However, flow control at this layer is performed end to end rather than across a single link. • Error control. Like the data link layer, the transport layer is responsible for error control. However, error control at this layer is performed process-to-process rather than across a single link. The sending transport layer makes sure that the entire message arrives at the receiving transport layer without error (damage, loss, or duplication). Error correction is usually achieved through retransmission Atria Institute of Technology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 77.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Session Layer • The services provided by the first three layers (physical, data link, and network) are not sufficient for some processes. • The session layer is the network dialog controller. • It establishes, maintains, and synchronizes the interaction among communicating system
  • 78.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 80.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Specific responsibilities of the session layer include the following: o Dialog control. The session layer allows two systems to enter into a dialog. It allows the communication between two processes to take place in either halfduplex (one way at a time) or full-duplex (two ways at a time) mode. o Synchronization. The session layer allows a process to add checkpoints, or synchronization points, to a stream of data. For example, if a system is sending a file of 2000 pages, it is advisable to insert checkpoints after every 100 pages to ensure that each 100-page unit is received and acknowledged independently. In this case, if a crash happens during the transmission of page 523, the only pages that need to be resent after system recovery are pages 501 to 523. Pages previous to 501 need not be resent.
  • 81.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Presentation Layer • The presentation layer is concerned with the syntax and semantics of the information exchanged between two systems. • Figure 2.13 shows the relationship between the presentation layer and the application and session layers.
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
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    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 85.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Specific responsibilities of the presentation layer include the following: o Translation. The processes (running programs) in two systems are usually exchanging information in the form of character strings, numbers, and so on. The information must be changed to bit streams before being transmitted. Because different computers use different encoding systems, the presentation layer is responsible for interoperability between these different encoding methods. The presentation layer at the sender changes the information from its sender-dependent format into a common format. The presentation layer at the receiving machine changes the common format into its receiver- dependent format. o Encryption. To carry sensitive information, a system must be able to ensure privacy. Encryption means that the sender transforms the original information to another form and sends the resulting message out over the network. Decryption reverses the original process to transform the message back to its original form. oCompression. Data compression reduces the number of bits contained in the information. Data compression becomes particularly important in the transmission of multimedia such as text, audio, and video
  • 86.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Application Layer • The application layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as electronic mail, remote file access and transfer, shared database management, and other types of distributed information services.
  • 87.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT Specific services provided by the application layer include the following: o Network virtual terminal. A network virtual terminal is a software version of a physical terminal, and it allows a user to log on to a remote host. To do so, the application creates a software emulation of a terminal at the remote host. The user's computer talks to the software terminal which, in turn, talks to the host, and vice versa. The remote host believes it is communicating with one of its own terminals and allows the user to log on o File transfer, access, and management. This application allows a user to access files in a remote host (to make changes or read data), to retrieve files from a remote computer for use in the local computer, and to manage or control files in a remote computer locally. o Mail services. This application provides the basis for e-mail forwarding and storage. o Directory services. This application provides distributed database sources and access for global information about various objects and services.
  • 88.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 89.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 90.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 91.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 92.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 93.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 94.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 95.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 96.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 97.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT
  • 98.
    Atria Institute ofTechnology, Bengaluru Department of MCA Computer Networks-22MCA14, ** Dr.Dattatreya P. Mankame, Professor & HOD, MCA, AIT