unit 1- Basics of Computer communication and networks.pptx

Basics of computer networks

1. MODULE- 1

2. Computer Networks(CN)- 23MCPC523

3. WHAT IS COMMUNICATION???

4. The act of sharing or exchanging information, ideas or feelings

5. What is NETWORK??????????????

6. A network is a set of devices connected by communication links.

7. Computer network

8. “Computer network’’ is a collection of autonomous computers interconnected by some technology for the purpose of sharing information and resources.

9. The connection can be via a copper wire; fiber optics, microwaves, infrared, and communication satellites can also be used. Ex: Internet

10. NETWORKING Interconnection of two or more independent computer to share resources and information Goals : Resource Sharing Reliability Cost Factor Communication Medium Need: Remote Access Sharing database Sharing printer

11. NETWORKING ARPANET(Advanced Research Projects Agency Network) Later named as Internet Founded by ARPA within US department Is a first packet switching network with TCP/IP INTERNET Network of network INTERSPACE Multiple user can communicate online Audio, video chat , 3D environment Advancement in internet

12. Hardware components in network Hardware components are: Nodes Servers Nodes: Also called as workstation It is a node attached to a network Server: Server shares hardware, software and data Dedicated Server Non-Dedicated Server

13. Non-Dedicated Server:

14. TYPES of network PAN LAN MAN WAN

15. TYPES of network

16. Personal Area Network (PAN) A PAN interconnects technology devices, typically within the range of a single user. ANs typically consist of laptops, smartphones, tablets, wearables . There are two types of PANs: wireless and wired.

17. The size of a PAN ranges from a few centimeters to a few meters. One of the most common real-world examples of a PAN is the connection between a Bluetooth earpiece and a smartphone.

18. TYPES of network LAN(Local Area Network):

19. Group of interconnected computers within a small area. (room, building, campus) Two or more pc's can form a LAN to share files, folders, printers, applications and other devices. Due to short distances, errors and noise are minimum.

20. Data transfer rate is 10 to 100 mbps. (1 Mbps is 10,00,000 bits/sec) Example: A computer lab in a school. WLAN(Wireless LAN) are also used these days Ex: wi-fi

21. MAN(Metropolitan Area Network):

22. Designed to extend over a large area. Connecting number of LAN's to form larger network, so that resources can be shared. Networks can be up to 5 to 50 km. Owned by organization or individual. Data transfer rate is low compare to LAN. Example: -> Organization with different branches located in the city. ->Cable TV

23. WAN(Wide Area Network):

24. Are country and worldwide network. Contains multiple LAN's and MAN's. Distinguished in terms of geographical range. It Uses satellites Data transfer rate depends upon the ISP provider and varies over the location. Best example is the internet.

25. What is internetwork??????

26. A collection of interconnected net- works is called an internetwork or internet . Network of network is internet The Internet uses ISP networks to connect enterprise networks, home networks, and many other networks.

27. NETWORK TOPOLOGIES It is a geographical appearance of computer and its resources in a network Types: Bus/Linear Topology Ring/Circular Topology Star Topology Graph Topology Tree Topology Mesh Topology

28. NETWORK TOPOLOGIES

29. Bus/Linear Topology node node node node node node Terminator Terminator

30. Bus/Linear Topology Advantages: Short cable length Easy Architecture Easy to extend(connect / disconnect computer) Disadvantages: Fault detection is difficult Entire n/w fails if main cable fails Terminators are required on both the end

31. Ring/ Circular Topology

32. Ring/ Circular Topology NODE NODE NODE NODE

33. Ring/ Circular Topology Advantages: Short cable length Each node has equal access to h/w and s/w Disadvantages: Node failure causes network failure Data flows in only one direction Network reconfiguration is difficult

34. Star Topology

35. Star Topology

36. Star Topology Advantages: Easy to connect and disconnect One device per connection Easy to detect and solve problems Failure of particular node does not stop working of entire network Disadvantages: Requires more cable length If central hub fails, entire network fails Requires costly and expensive hub

37. Tree Topology

38. Tree Topology HUB NODE NODE NODE NODE HUB NODE NODE HUB HUB NODE NODE NODE

39. MESH TOPOLOGY

40. MESH TOPOLOGY Each node is connected to more than one node to provide an alternative root in the case the host is not working or too busy mesh topology is excellent for long distance networking

41. Full connectivity Since all computers are connected to each other there exists a link between all the host

42. packets It’s a physical thing appear on a wire in a network. The original data is divided into small pieces called as packets

43. Switching Techniques Circuit Switching Packet Switching

44. Circuit switching First the complete connection is made between 2 devices then data is transmitted This is end to end connection Ex: Telephone call

45. packet switching Here message is divided into packets

46. A Comparison

47. Communication Mode Simplex Mode : Terminal A Terminal B

48. Half Duplex Terminal A Terminal B OR

49. Full Duplex Terminal A Terminal B AND

50. Distributed system Distributed System is a collection of autonomous computer systems that are physically separated but are connected by a centralized computer network that is equipped with distributed system software. Ex: WWW

51. USES OF COMPUTER NETWORKS Business Applications Home Applications Mobile Users Social Issues

52. Business Applications Sharing physical resources such as printers, backup systems, information etc client-server model email Voice over IP ( VoIP ) Desktop sharing e-commerce

53. Home Applications peer-to-peer communication person-to-person communication electronic commerce

54. Entertainment instant messaging TV shows now reach many homes via IPTV ( IP TeleVision ) Ubiquitous computing security systems that include door and window sensors--- IoT

55. Mobile Users Text messaging or texting Smart phones GPS (Global Positioning System) Wearable computers m-commerce NFC (Near Field Communication)

56. M-commerce Using cell phones for commercial transactions online, including the purchase and sale of products, online banking, and paying bills

57. NFC (Near Field Communication) Near-field communication is a set of communication protocols that enables communication between two electronic devices Ex: Mobile payments, such as phone Pay and Google Pay

58. Social Issues Social networks Message boards and content sharing sites Printing , Publishing E-mail

59. message boards a website or web page where users can post comments about a particular issue or topic and reply to other users' postings.

60. NETWORK HARDWARE There are two types of transmission technology that are in widespread use: -> point-to-point links. -> broadcast links

61. Point-to-point transmission with exactly one sender and exactly one receiver is sometimes called unicasting . When a packet with this code is transmitted, it is received and processed by every machine on the network. This mode of operation is called broadcasting .

62. Protocols Basically, a protocol is an agreement between the communicating peers on how communication is to proceed.

63. Protocol Hierarchies: Networks are collection of layers Each layer is to offer certain services The number of layers, the name of each layer, the contents of each layer, and the function of each layer differ from network to network The purpose of each layer is to offer certain services to the higher layers

64. NETWORK SOFTWARE A five-layer network

65. A set of layers and protocols is called a network architecture . Ex: A five-layer network The physical medium through which actual communication occurs. Virtual communication is shown by dotted lines and physical communication by solid lines.

66. Design Issues for the Layers Error detection: There is a chance that some of these bits will be received damaged (inverted) due to fluke electrical noise, random wireless signals, hardware flaws, software bugs and so on. One mechanism for finding errors in received information uses codes for error detection .

67. 2. Routing: Another reliability issue is finding a working path through a network is called routing.

68. 3. Addressing Since there are many computers on the network, every layer needs a mechanism for identifying the senders and receivers that are involved in a particular message. This mechanism is called addressing or naming

69. Connection-Oriented Versus Connectionless Service Both Connection-oriented service and Connection-less service are used for the connection establishment between two or more devices. These types of services are offered by the network layer. 

70. Connection-Oriented Connection-oriented service  is related to the telephone system. It includes connection establishment and connection termination. In a connection-oriented service, the Handshake method is used to establish the connection between sender and receiver.

71. Connectionless Service Connection-less service  is related to the postal system. It does not include any connection establishment and connection termination. Connection-less Service does not give a guarantee of reliability. In this, Packets do not follow the same path to reach their destination. 

72. Service Primitives A service is formally specified by a set of primitives (operations) available to user processes to access the service. Primitive Meaning LISTEN Block waiting for an incoming connection CONNECT Establish a connection with a waiting peer ACCEPT Accept an incoming connection from a peer RECEIVE Block waiting for an incoming message SEND Send a message to the peer DISCONNECT Terminate a connection

73. REFERENCE MODELS Two important network architectures: the OSI reference model and the TCP/IP reference model.

74. The OSI Reference Model OSI ( Open Systems Interconnection ) It is a 7-layer architecture with each layer having specific functionality to perform. All these 7 layers work collaboratively to transmit the data from one person to another across the globe. 

75. Data flows through the OSI model in a step-by-step process: Application Layer:  Applications create the data. Presentation Layer:  Data is formatted and encrypted. Session Layer:  Connections are established and managed. Transport Layer:  Data is broken into segments for reliable delivery. Network Layer : Segments are packaged into packets and routed. Data Link Layer:  Packets are framed and sent to the next device. Physical Layer:  Frames are converted into bits and transmitted physically.

76. The Application Layer The application layer contains a variety of protocols that are commonly needed by users. One widely used application protocol is HTTP ( Hyper Text Transfer Protocol ) When a browser wants a Web page, it sends the name of the page it wants to the server hosting the page using HTTP. The server then sends the page back. Other application protocols are used for file transfer, electronic mail, and network news. 

77. Presentation layer Is concerned with the syntax and semantics of the information transmitted. Presentation layer includes Encryption , decryption of message The data from the application layer is extracted here and manipulated as per the required format to transmit over the network. 

78. The Session Layer The session layer allows users on different machines to establish sessions between them. This layer is responsible for the establishment of connection, maintenance of sessions, and authentication, and also ensures security.

79. The Transport Layer This layer accepts the message from the (session) layer, and breaks the message into smaller units called segments . Each of the segments produced has a header associated with it. The transport layer at the destination station reassembles the message. It ensure that the pieces all arrive correctly at the other end. The transport layer is a true end-to-end layer; it carries data all the way from the source to the destination.

80. The Network Layer The network layer takes care of packet routing i.e. selection of the shortest path to transmit the packet, from the number of routes available. The sender & receiver’s  IP address es are placed in the header by the network layer. 

81. The Data Link Layer The packet received from the Network layer is further divided into frames depending on the frame size of the NIC(Network Interface Card). DLL also encapsulates Sender and Receiver’s MAC address in the header.  Detect and possibly correct errors that may occur in the physical layer. When a packet arrives in a network, it is the responsibility of the DLL to transmit it to the Host using its  MAC address (Media Access Control)

82. Switch & Bridge are Data Link Layer devices . Layer 2 will receive the “packet” from above and encapsulate it inside a “frame”. This frame will have the hardware source and destination addresses ( MAC address ) and will then move down to the wire (physical layer).

83. Physical layer The lowest layer of the OSI reference model is the physical layer. It is responsible for the actual physical connection between the devices. The physical layer contains information in the form of  bits.

84. Example: Luffy sends an e-mail to his friend Zoro. Step 1:  Luffy interacts with e-mail application like  Gmail ,  outlook , etc. Writes his email to send. (This happens in  Layer 7: Application layer ) Step 2:  Mail application prepares for data transmission like encrypting data and formatting it for transmission. (This happens in  Layer 6: Presentation Layer ) Step 3:  There is a connection established between the sender and receiver on the internet. (This happens in  Layer 5: Session Layer ) Step 4:  Email data is broken into smaller segments. It adds sequence number and error-checking information to maintain the reliability of the information. (This happens in  Layer 4: Transport Layer )

85. Step 5:  Addressing of packets is done in order to find the best route for transfer. IP address is added here. (This happens in  Layer 3: Network Layer ) Step 6:  Data packets are encapsulated into frames, then MAC address is added for local devices and then it checks for error using error detection. (This happens in  Layer 2: Data Link Layer ) Step 7:  Lastly Frames are transmitted in the form of electrical/ optical signals over a physical network medium like ethernet cable or WiFi .

86. https://www.geeksforgeeks.org/open-systems-interconnection-model-osi/

87. TCP/IP The ability to connect multiple networks in satellite and radio networks way was one of the major design goals. This architecture later became known as the TCP/IP Reference Model

88. Link Layer Link layer is lowest layer in the model, which describes what links such as serial lines and classic Ethernet must do to meet the needs of this connectionless internet layer. Error prevention and “framing” are also provided by this layer.

89. The Internet Layer Its job is to permit hosts to inject packets into any network and have them travel in- dependently to the destination (potentially on a different network). They may even arrive in a completely different order than they were sent, in which case it is the job of higher layers to rearrange them, if in-order delivery is desired.

90. The Internet Layer It also defines the packet format and protocol called called IP, ICMP . The job of the internet layer is to deliver IP packets where they are supposed to go.

91. The Transport Layer The TCP/IP transport layer protocols exchange data receipt acknowledgments and retransmit missing packets to ensure that packets arrive in order and without error. Transmission Control Protocol (TCP) and User Datagram Protocol are transport layer protocols at this level (UDP) for the reliable transfer of data.

92. The Application Layer It is responsible for end-to-end communication and error-free delivery of data. It shields the upper-layer applications from the complexities of data. The three main protocols present in this layer are: HTTP, SMPT, FTP, DNS and HTTPS, SSH(Secure Shell), NTP(Network Time Protocol) for fetching pages on the web.

93. Parameters OSI Model TCP/IP Model Full Form OSI stands for Open Systems Interconnection. TCP/IP stands for Transmission Control Protocol/Internet Protocol. Layers It has 7 layers. It has 4 layers. Usage It is low in usage. It is mostly used. Approach It is vertically approached. It is horizontally approached. Delivery Delivery of the package is guaranteed in OSI Model. Delivery of the package is not guaranteed in TCP/IP Model. Replacement Replacement of tools and changes can easily be done in this model. Replacing the tools is not easy as it is in OSI Model. Reliability It is less reliable than TCP/IP Model. It is more reliable than OSI Model.

94. IP address

95. IP Address IP( Internet Protocol )address which uniquely identify each device in a network.

96. IP Address An IP address can be either private or public. Private IP addresses are used for devices on a private network, such as a home or office network.  These private IP addresses are commonly used for devices like computers, printers, and routers in a home or office network

97. Public IP addresses, on the other hand, are unique addresses that can be accessed directly from the Internet. These addresses are typically assigned by an ISP (Internet Service Provider) and are used for devices that need to be accessible from the Internet, such as servers, websites, and email servers.

98. THE PHYSICAL LAYER

99. Transmission medium It is a medium in which computer are connected (wired or wireless)

100. Transmission medium It is a medium in which computer are connected (wired or wireless) Types: Guided Media( Wired) Unguided Media(Wireless) Transmission medium Guided(Wired) Persistent Storage Twisted Pair Cable Coaxial Cable Optical Fiber Power Lines UnGuided (Wireless) Electromagnetic Spectrum Frequency hopping spread spectrum Direct Sequence spread spectrum Ultra wideband communication

101. Guided medium Persistent Storage Most common method where data is written onto persistent storage and transfer it to the destination system. More cost effective method For moving large amount of data this method is used Example : Amazon’s snow mobile

102. Guided medium 2)Twisted pair cable Most commonly used medium Consists of 2 wires wrapped to each other Used in telephone wiring as a Voice Grade Medium(VGM) Also used as Data Grade Medium(DGM)

103. Guided medium Twisted pair cable Types: Unshielded Twisted Pair(UTP) shielded Twisted Pair(STP)

104. Unshielded Twisted Pair(UTP): Comes in different category Maximum distance coverage is 100 meters

105. Shielded Twisted Pair(STP): Individual pair has a shielding here It protects from external interference because of shielding Heavy and costly due to shielding

106. Twisted pair Cable Application: LAN , Telephone wire Advantages: Maintenance is easy It has a low weight Less expensive Disadvantage: Because of low bandwidth not suitable for broadband Incapable of carrying signal over long distance without repeater

107. Coaxial cable Better shielding and greater bandwidth Used for longer distance It has stiff copper wire as a core, surrounded by insulated material The insulator is encased by a cylindrical conductor Outer conductor is covered by protective plastic

108. Coaxial cable Commonly used cables are: THICKNET and THINNET THICKNET: thicker than thinnet It can be upto 500 meters THINNET: It is thinner It can be upto 185 meters

109. Coaxial cable

110. Telephone trunk lines Broadband internet and cable television services High-speed computer data busses Connecting radio transmitters and receivers to their antennas Professional broadcasting, home theater systems, and security camera installations Application:

111. Optical Fibers Consists of central glass/glass like material Fiber optic cables are used They use light signal to carry data Fiber-optic cables use fast-traveling pulses of light to transfer digital information.  May be LED or laser lights are used Bandwidth is very high They permit transmission over longer distances and at higher  bandwidths  (data transfer rates) Fibers are used instead of metal  wires .

112. Optical Fibers

113. Optical Fibers Advantages: Not effected by external noise Suitable for industrial environment Higher carrying capacity Long lifespan Less signal degradation

114. Optical Fibers Disadvantages: Installation Problem(very complex wires) extra care must be taken If you bend them too much, they will break. The optical fibers are more expensive to install, and they have to be installed by the specialists. Special test equipment is often required to the optical fiber.

115. Power Lines Used to deliver electrical power to houses and within houses Is a low rate communication It is designed to distribute power signal Example: Power lines to TV , Washing Machine etc

116. Transmission medium It is a medium in which computer are connected (wired or wireless) Types: Guided Media( Wired) Unguided Media(Wireless) Transmission medium Guided(Wired) Persistent Storage Twisted Pair Cable Coaxial Cable Optical Fiber Power Lines UnGuided (Wireless) Electromagnetic Spectrum Frequency hopping spread spectrum Direct Sequence spread spectrum Ultra wideband communication

117. Unguided/Wireless Media Electromagnetic Spectrum Frequency hopping spread spectrum Direct Sequence spread spectrum Ultra wideband communication

118. Electromagnetic Spectrum One of the wireless communication technique where Electromagnetic waves are used as they can propagate through space When an antenna of the appropriate size is attached to an electrical circuit, the electromagnetic waves can be broadcast efficiently All wireless communication(Radio, Microwave, Infrared, Laser) is based on this principle.

119. Electromagnetic Spectrum Types Radio wave Microwave Infrared Laser/ Light Transmission

120. Frequency hopping spread spectrum When we see TV and listen to radio we tune into fixed channel. These type of communication has 3 problems: 1) Interference 2) Jamming 3) Interception These will slow down communication and security problem

121. Frequency hopping spread spectrum

122. Frequency hopping spread spectrum To solve these issues FHSS method is used where it uses spread spectrum techniques Here a signal generated with a particular bandwidth is spread within the frequency band, thus reduces interference and jamming.

123. Different sender uses different hoping pattern at different time to send the data

124. These type of modulation methods are used in : military GPS cordless phones

125. Direct Sequence spread spectrum

126. Direct-sequence spread spectrum each channel may carry different information, data signals, or time slots for different applications within the same network. Direct-sequence spread spectrum has also been used to transmit data that is encrypted and, in some processes, it is used to transmit non-data signals like power signaling or control signals.

127. Ultra wide band communication ultra-wideband  is a radio technology used for a wide range of frequency channels and having low energy short-range. It is used for short-range wireless communication protocols like  Bluetooth  and  Wi-Fi .  It can work on a wide range of frequencies in which we can send short pulses of information at a moment.

128. Radio Frequency(RF) Radio frequencies are used Can travel long distance and penetrate buildings , walls easily So used in indoor and outdoor communication They are omnidirectional It includes transmitter and receiver They are frequency dependent. Ex: Radio, TV

129. Radio Frequency(RF)

130. Radio Frequency(RF) Advantages Cheaper Free from requirement of land Covers difficult areas Disadvantage It will be effected by weather Not very secure Path loss

131. Micro Wave transmission It includes Transmitter, Receiver and atmosphere They are directional travel in straight line Repeaters are needed for long distance Microwave transmission antennas are used At lower frequency it do not pass to buildings It has shorter wavelength Used in TV, sensors, Telephones

132. Micro Wave transmission

133. Micro Wave transmission Advantages No cables are used so cheap Avoids of land problem Communication can be done on any area easily Disadvantage Insecure Signal may split up It will be effected by weather condition

134. Infrared Communication Infrared light is used here It can propagate throughout the room but not penetrate walls Commonly used in Remote Controls, handheld devices, palmtops It is secure mode of communication

135. LASER Communication It travels in a straight line with narrow beam It’s a unidirectional communication It requires Laser transmitter and the receiver Has higher speed then other modes But it can be effected by weather condition

136. NASA to use laser communication for high-speed space ‘internet’