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Networking lec1 4

Computer Networking

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Networking lec1 4

  1. 1. Computer Networking Unit 1 Dr. V. Dutta
  2. 2. Subject : Computer Networks (IC-701) Unit 1 Computer Network, Goals and Applications, Reference models – OSI and TCP/IP. A Comparative study. Network hardware – LAN, MAN and WAN and topologies, Network Software –protocol hierarchies, design issues for the layers, Connection Oriented and connection less services, Switching Techniques – Circuit Switching, Message switching, Packet Switching. MCA VIISec B Computer Networking Class-Notes 2
  3. 3. Computer Network • A computer network is a group of computers that use a set of common communication protocols over digital interconnections for the purpose of sharing resources located on or provided by the network nodes. • A network consists of two or more computers connected together, and they can communicate and share resources (e.g. information) The System can be geographically located anywhere. MCA VIISec B Computer Networking Class-Notes 3
  4. 4. Network Goals • Allow activities on multiple computer systems to communicate with each other • Shared memory, files, or data • Message passing • Remote Procedure Call • Integrated applications — distributed across physical space • Create abstractions that make these (relatively) transparent MCA VIISec B Computer Networking Class-Notes 4
  5. 5. Computer Network Features • Communication speed • File sharing • Back up and Roll back is easy • Software and Hardware sharing • Security • Scalability • Reliability MCA VIISec B Computer Networking Class-Notes 5
  6. 6. Advantages • Sharing devices such as printers saves money. • Site (software) licenses are likely to be cheaper than buying several standalone licenses. • Files can easily be shared between users. • Network users can communicate by email and instant messenger. MCA VIISec B Computer Networking Class-Notes 6
  7. 7. Disadvantages • Purchasing the network cabling and file servers can be expensive. • Managing a large network is complicated, requires training and a network manager usually needs to be employed. • If the file server breaks down the files on the file server become inaccessible. Email might still work if it is on a separate server. The computers can still be used but are isolated. • Viruses can spread to other computers throughout a computer network. • There is a danger of hacking, particularly with wide area networks. Security procedures are needed to prevent such abuse, eg a firewall. MCA VIISec B Computer Networking Class-Notes 7
  8. 8. Types of Networks Depending on one’s perspective, we can classify networks in different ways • Based on transmission media: Wired (UTP, coaxial cables, fiber-optic cables) and Wireless • Based on network size: LAN and WAN (and MAN) • Based on management method: Peer-to-peer and Client/Server • Based on topology (connectivity): Bus, Star, Ring etc MCA VIISec B Computer Networking Class-Notes 8
  9. 9. 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. MCA VIISec B Computer Networking Class-Notes 10
  10. 10. 11 Peer-to-Peer Networks •Peer-to-peer network is also called workgroup •No hierarchy among computers  all are equal •No administrator responsible for the network MCA VIISec B Computer Networking Class-Notes
  11. 11. 12 •Advantages of peer-to-peer networks: • Low cost • Simple to configure • User has full accessibility of the computer •Disadvantages of peer-to-peer networks: • May have duplication in resources • Difficult to uphold security policy • Difficult to handle uneven loading •Where peer-to-peer network is appropriate: • 10 or less users • No specialized services required • Security is not an issue • Only limited growth in the foreseeable future MCA VIISec B Computer Networking Class-Notes
  12. 12. 13 Clients and Servers 1. Network Clients (Workstation) Computers that request network resources or services 1. Network Servers Computers that manage and provide network resources and services to clients  Usually have more processing power, memory and hard disk space than clients  Run Network Operating System that can manage not only data, but also users, groups, security, and applications on the network  Servers often have a more stringent requirement on its performance and reliability MCA VIISec B Computer Networking Class-Notes
  13. 13. 14 Advantages of client/server networks • Facilitate resource sharing – centrally administrate and control • Facilitate system backup and improve fault tolerance • Enhance security – only administrator can have access to Server • Support more users – difficult to achieve with peer-to-peer networks Disadvantages of client/server networks • High cost for Servers • Need expert to configure the network • Introduce a single point of failure to the system MCA VIISec B Computer Networking Class-Notes
  14. 14. P2P topology is where one device is directly connectedwith another device. In PTM, Data transmittedfrom the centralbase stationis broadcastingtoall the subscribersBut datacoming from a subscriber is only received by the base station. PTM topology is typically used in wireless LAN, and wireless WAN. MCA VIISec B Computer Networking Class-Notes 15
  15. 15. 16 Topology ― 3 basic types Physical, Logical and Hybrid Bus Topology(Daisy chain) Ring Topology Star Topology Hub MCA VIISec B Computer Networking Class-Notes
  16. 16. 17 Bus Topology & Ring Topology • Simple and low-cost • A single cable called a trunk (backbone, segment) • Only one computer can send messages at a time • Passive topology - computeronly listen for, not regeneratedata Both are not secure, not fault tolerantand difficult to trouble shoot. Star Topology • Each computerhas a cable connected to a single point • More cabling, hence higher cost • All signals transmissionthroughthe hub; if down, entire network down • Depending on the intelligence of hub, two or more computersmay send message at the same time. MCA VIISec B Computer Networking Class-Notes
  17. 17. 1. In star topology, the nodes are connected to the central hub or router. In ring topology, every node is connected to it’s left and right side nodes. 2. In star topology, only hub is failure point. In ring topology, every nodes are failure point. 3. The cost of star topology is high. The cost of ring topology is low. 4. In star topology, the information is travel from central hub or router to all the nodes. In ring topology, the information is travel from nodes to nodes in ring manner in one direction. 5. The cables are required in star topology more than the ring topology. The cables are required in ring topology less than the star topology. 6. There are n links in Star topology, if there are n nodes. There are also n links in ring topology, if there are n nodes present. 7. A new cable is added to the central hub to add a new node. Whereas to add a new node in ring topology, the connection must be broken. MCA VIISec B Computer Networking Class-Notes 18
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  19. 19. Applications of 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 • Centralized Control • Distributed processing (GRID Computing) • Security is good - users cannot see other users' files unlike on stand-alone machines. • Data is easy to backup as all the data is stored on the file server. MCA VIISec B Computer Networking Class-Notes 20
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  22. 22. *All People Seems to Need DataProcessing MCA VIISec B Computer Networking Class-Notes 23
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  35. 35. TCP/IP that is Transmission Control Protocol and Internet Protocol was developed by Department of Defense's Project Research Agency (ARPA, later DARPA) as a part of a research project of network interconnection to connect remote machines. The features that stood out during the research, which led to making the TCP/IP reference model were: Support for a flexible architecture. Adding more machines to a network was easy. The network was robust, and connections remained intact until the source and destination machines were functioning. The overall idea was to allow one application on one computer to talk to(send data packets) another application running on different computer, using multiple paths. MCA VIISec B Computer Networking Class-Notes 36
  36. 36. Network issues • Addressing • Routing • Name Resolution (By DNS) • Flow & Control • Interoperability MCA VIISec B Computer Networking Class-Notes 37
  37. 37. TCP/IP Reference Model is a four-layered suite of communication protocols. ... TCP stands for Transmission Control Protocol and IP stands for Internet Protocol. The four layers in the TCP/IP protocol suite are − Host-to- Network Layer −It is the lowest layer that is concerned with the physical transmissionof data. The Link layer is sometimes referred to as the Network access layer. The Transport layer is sometimes called the Host-to-Hostlayer. data segments packets Frames bits MCA VIISec B Computer Networking Class-Notes 38
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  41. 41. Q. Find the Network ID , SubnetMask and Class for the given IP? Q. Convert Network ID/IP into Binary. MCA VIISec B Computer Networking Class-Notes 42
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  44. 44. Convert into Binary : IP 192.168.37.200 27 26 25 24 23 22 21 20 128 64 32 16 8 4 2 1 1 1 0 0 0 0 0 0 192 1 0 1 0 1 0 0 0 168 0 0 1 0 0 1 0 1 37 1 1 0 0 1 0 0 0 200 200 128+64+8 192 putting‘1’ for 128and 64 rest ‘0’ 168 putting‘1’ for 128+32 +8 37  32+4+1 As Shown above, we can take ‘1’for the numbers whose sum is 192 i.e 128+64, similarly for 168  128+32+8 so on .. Therefore binary form is: 11000000.10101001.00100101.10010001 MCA VIISec B Computer Networking Class-Notes 45
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  47. 47. To find Network ID, usablehost and broadcastID? e.g. 1) 160.10.20.30 Network ID : 160.10.0.0 Broadcast ID: 160.10.255.255 In class B 2) 17.210.201.210 Network ID : 17.0.0.0 Broadcast ID: 17.255.255.255 Usable ID : . 28*3 -2 = 224 -1 in Class A As the number of usable host in this (ClassB) IP is 8bits + 8 bits = 16 therefore its 216 (Total IPs) minus 2. 216 – 2 = 65534 usable IPs can be given to computer. As 1st (networkIP) and last (Broadcast)oneis Reserved. MCA VIISec B Computer Networking Class-Notes 48
  48. 48. Switching Techniques • In large networks, there can be multiple paths from sender to receiver. The switching technique will decide the best route for data transmission. • Switching technique is used to connect the systems for making one-to-one communication. MCA VIISec B Computer Networking Class-Notes 49
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  51. 51. Message Switching MCA VIISec B Computer Networking Class-Notes 52
  52. 52. Packet switching method uses two routing 1. Datagram Packet Switching 2. Virtual Circuit Packet Switching A virtual circuit network uses a fixed path for a particular session, after which it breaks the connection and another path has to be set up for the next the next session. A Datagram based network is a true packet switched network. There is no fixed path for transmitting data MCA VIISec B Computer Networking Class-Notes 53
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  54. 54. MCA VIISec B Computer Networking Class-Notes 55 1. Virtual Circuit Packet Switching 1. DatagramPacket Switching Virtual circuits are connection-oriented,whichmeans that there is a reservationof resources like buffers, bandwidth, etc. for the time during whichthe newly setup VC is going to be used by a data transfer session. It is connectionless service.There is no needfor reservationof resources as there is no dedicatedpathfor a connectionsession. A virtual circuit network uses a fixedpathfora particular session,afterwhichit breaks the connectionandanother path has to be set up for the next the next session. A Datagrambasednetwork is a true packet switched network. There is no fixedpathfortransmittingdata. All the packets follow the same pathandhence a global header is required only for the first packet of connection and other packets will not require it. Every packet is free to choose any path,andhence all the packets must be associatedwitha header containing informationabout the source andthe upper layer data. Packets reachinorder to the destinationas data follows the same path. Data packets reachthe destinationinrandomorder, whichmeans they need not reachin the order in which they were sent out. Virtual Circuits are highly reliable. Datagramnetworks are not as reliable as Virtual Circuits. Implementationof virtual circuits is costly as eachtime a new connectionhas to be set up withreservationof resources andextra informationhandlingat routers. It is always easy andcost-efficient toimplement datagramnetworks as there is no need of reserving resources andmakinga dedicatedpatheachtime an applicationhas to communicate.
  55. 55. Assignment 1-2. • LAN, WAN, PAN, HAN, CAN, MAN, SAN, WLAN, BAN, NAN etc. • Make ppt of : Router, Switch, Hub, Repeater, Gateway, Connectors, Cables types. Write 3 sentences on each. • Take any three IP address of Each Class A, B and C : 1. convert it into binary 2. Find the network ID 3. Find the usable ID MCA VIISec B Computer Networking Class-Notes 56

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