MCA AKTU computer_networrks_Unit 01.pptx

Computer network chapter number one is made in PPT format for MCA students

1. 9/29/2023 1 Introduction to Computer Networks INTRODUCTION TO COMPUTER NETWORKS Introduction to Computer Networks

2. 9/29/2023 2 Computer Networks Computer network connects two or more autonomous computers. The computers can be geographically located anywhere. Introduction to Computer Networks

3. 9/29/2023 3 LAN, MAN & WAN Introduction to Computer Networks Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Network) Network in a City is call MAN (Metropolitan Area Network) Network spread geographically (Country or across Globe) is called WAN (Wide Area Network)

4. 9/29/2023 4 Applications of Networks Introduction to Computer Networks Resource Sharing. Hardware (computing resources, disks, printers) Software (application software) Information Sharing. Easy accessibility from anywhere (files, databases) Search Capability (WWW) Communication. Email Message broadcast Remote computing. Home Application. Mobile user. Social Issues.

5. 9/29/2023 5 Network Topology The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions. Introduction to Computer Networks

6. 9/29/2023 6 Bus Topology Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable. Introduction to Computer Networks

7. 9/29/2023 7 Star & Tree Topology Introduction to Computer Networks The star topology is the most commonly used architecture in Ethernet LANs. When installed, the star topology resembles spokes in a bicycle wheel. Larger networks use the extended star topology also called tree topology. When used with network devices that filter frames or packets, like bridges, switches, and routers, this topology significantly reduces the traffic on the wires by sending packets only to the wires of the destination host.

8. 9/29/2023 8 Ring Topology Introduction to Computer Networks A frame travels around the ring, stopping at each node. If a node wants to transmit data, it adds the data as well as the destination address to the frame. The frame then continues around the ring until it finds the destination node, which takes the data out of the frame. Single ring – All the devices on the network share a single cable Dual ring – The dual ring topology allows data to be sent in both directions.

9. 9/29/2023 9 Mesh Topology The mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance. It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions. Implementing the mesh topology is expensive and difficult. Introduction to Computer Networks

10. 9/29/2023 10 Network Components Introduction to Computer Networks Physical Media Interconnecting Devices Computers Networking Software Applications

11. 9/29/2023 11 Networking Media Networking media can be defined simply as the means by which signals (data) are sent from one computer to another (either by cable or wireless means). Introduction to Computer Networks

12. 9/29/2023 12 Networking Devices Introduction to Computer Networks HUB, Switches, Routers, Wireless Access Points, Modems etc.

13. 9/29/2023 13 Computers: Clients and Servers In a client/server network arrangement, network services are located in a dedicated computer whose only function is to respond to the requests of clients. The server contains the file, print, application, security, and other services in a central computer that is continuously available to respond to client requests. Introduction to Computer Networks

14. 9/29/2023 14 Networking Protocol: TCP/IP Introduction to Computer Networks

15. 9/29/2023 15 Applications E-mail Searchable Data (Web Sites) E-Commerce News Groups Internet Telephony (VoIP) Video Conferencing Chat Groups Instant Messengers Internet Radio Introduction to Computer Networks

16. 9/29/2023 16 The OSI Model An ISO (International standard Organization) that covers all aspects of network communications is the Open System Interconnection (OSI) model . An open system is a model that allows any two different systems to communicate regardless of their underlying architecture (hardware or software). The OSI model is not a protocol; it is model for understanding and designing a network architecture that is flexible, robust and interoperable.

17. 9/29/2023 17 The OSI model is a layered framework for the design of network systems that allows for communication across all types of computer systems. The OSI model is built of seven ordered layers: (layer 1) physical layer (layer 2) data link (layer 3) network layer (layer 4) transport layer (layer 5) session layer (layer 6) presentation layer (layer 7) application layer

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19. 9/29/2023 19 Physical Layer The physical layer coordinates the functions required to transmit a bit stream over a physical medium. It also defines the procedures and functions that physical devices and interfaces have to perform for transmission occur . The physical layer is responsible for transmitting individual bits from one node to the next.

20. 9/29/2023 20 Physical layer The physical layer is concerned with the following: Physical characteristics of interfaces and media : The physical layer defines the characteristics of the interface between devices and the transmission media, including its type. Representation of the bits : the physical layer data consist of a stream of bits without any interpretation. To be transmitted, bits must be encoded into signals –electrical or optical-. The physical layer defines the type of encoding . Data rate : The physical layer defines the transmission rate, the number of bits sent each second.

21. 9/29/2023 21 Physical Layer Line configuration: the physical layer is concerned with the connection of devices to the medium. Physical topology Transmission Mode

22. 9/29/2023 22 Data Link Layer The data link layer transforms the physical layer, a raw transmission facility, to a reliable link and is responsible for node-to-node delivery. It makes the physical layer appear error free to the upper layer (network layer). The data link layer is responsible for transmitting frames from one node to the next.

23. 9/29/2023 23 Node-to-node delivery

24. 9/29/2023 24 Functions of the data link layer: Framing . The data link layer divides the stream of bits received from the network layer into 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 physical address of the sender (source address) and/or receiver (destination address) 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 one network to the next.

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26. 9/29/2023 26 Flow Control . If the rate at which the data are absorbed by the receiver is less than the rate produced in the sender, the data link layer imposes a flow control mechanism to prevent 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. Error control is normally achieved through a trailer 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 time.

27. 9/29/2023 27 Network Layer The Network layer is responsible for the source-to-destination delivery of a packet possible across multiple networks. If two systems are connected to the same link, there is usually no need for a network layer. However, if the two systems are attached to different networks, there is often a need for the network layer to accomplish source-to-destination delivery.

28. 9/29/2023 28 Network Layer Functions: Logical addressing . Routing The network layer is responsible for the delivery of packets from the original source to the final destination.

29. 9/29/2023 29 Source-to-destination delivery

30. 9/29/2023 30 Logical addressing . The physical addressing implemented by the data link layer handles the addressing problem locally. The network layer adds a header to the packet coming from the upper layer, among other things, includes the logical address of the sender and receiver. Routing. When independent networks or links are connected together to create an internetwork (a network of networks) or a large network, the connecting devices (called routers or gateways) route or switch the packets to their final destination.

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32. 9/29/2023 32 Transport Layer The transport layer is responsible for process-to-process delivery of the entire message. The network layer oversees host-to-destination delivery of individual packets, it does not recognize any relationship between those packets. The transport layer ensures that the whole message arrives intact and in order, overseeing both error control and flow control at the process-to-process level.

33. 9/29/2023 33 Transport layer The transport layer is responsible for delivery of a message from one process to another.

34. 9/29/2023 34 Reliable process-to-process delivery of a message

35. 9/29/2023 35 Functions of the transport layer Port addressing:computer often run several processes (running programs) at the same time. Process-to-process delivery means delivery from a specific process on one computer to a specific process on the other. The transport layer header include a type of address called 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.

36. 9/29/2023 36 Functions of the transport layer Segmentation and reassembly : a message is divided into transmittable segments, each having a sequence number. These numbers enable the transport layer to reassemble the message correctly upon arrival at the destination. 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.

37. 9/29/2023 37 Functions of the transport layer Flow control : the transport layer performs a flow control end to end. The data link layer performs flow control across a single link. Error control : the transport layer performs error control end to end. The data link layer performs control across a single link.

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39. 9/29/2023 39 The session layer is the network dialog controller . It was designed to establish, maintain, and synchronize the interaction between communicating devices. The presentation layer was designed to handle the syntax and semantics of the information exchanged between the two systems. It was designed for data translation, encryption, decryption, and compression. The application layer enables the user to access the network. It provides user interfaces and support for services such electronic email, remote file access, WWW, and so on.

40. 9/29/2023 40 Application layer The application layer is responsible for providing services to the user.

41. 9/29/2023 41 Summary of duties

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