Arvind Singh


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Arvind Singh

  2. 2. Agenda <ul><li>Basic LAN Definition </li></ul><ul><li>Network Hardware </li></ul><ul><li>Network Media </li></ul><ul><li>Sample LAN Implementation </li></ul>
  3. 3. LANs <ul><li>Definition – LAN ( local area network) </li></ul><ul><ul><li>Is a group of computers and associated devices that share a common communications line or wireless link and typically </li></ul></ul><ul><ul><li>share the resources of a single processor or server within a </li></ul></ul><ul><ul><li>small geographic area (for example, within an office building). </li></ul></ul><ul><ul><li>Usually, the server has applications and data storage that are shared in common by multiple computer users. </li></ul></ul><ul><ul><li>A local area network may serve as few as two or three users (for example, in a home network) or many as thousands of users. </li></ul></ul>
  5. 5. LANs <ul><li>Characteristics – LAN </li></ul><ul><ul><li>Topology </li></ul></ul><ul><ul><ul><li>The geometric arrangement of devices on the network or the shape of a local-area network (LAN) or other communications system. </li></ul></ul></ul><ul><ul><li>Protocols </li></ul></ul><ul><ul><ul><li>The rules and encoding specifications for sending data. The protocol defines the format and meaning of the data that is exchanged. The protocols also determine whether the network uses a peer-to-peer or client/server architecture. </li></ul></ul></ul><ul><ul><li>Media </li></ul></ul><ul><ul><ul><li>Devices can be connected by twisted-pair wire, coaxial cables, or fiber optic cables. Some networks do without connecting media altogether, communicating instead via radio waves . </li></ul></ul></ul>
  6. 6. LANs <ul><ul><li>Topology types </li></ul></ul><ul><ul><li>bus topology : All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systems use a bus topology. </li></ul></ul><ul><ul><li>star topology : All devices are connected to a central hub. Star networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the hub. This is not much of a problem anymore with the widespread deployment of switches. </li></ul></ul><ul><ul><li>ring topology : All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it. Ring topologies are relatively expensive and difficult to install, but they offer high bandwidth and can span large distances. </li></ul></ul>
  7. 7. Network Hardware <ul><li>Hub </li></ul><ul><ul><li>An unintelligent network device that sends one signal to all of the stations connected to it. </li></ul></ul><ul><ul><li>All computers/devices are competing for attention because it takes the data that comes into a port and sends it out all the other ports in the hub. </li></ul></ul><ul><ul><li>Traditionally, hubs are used for star topology networks, but they are often used with other configurations to make it easy to add and remove computers without bringing down the network . </li></ul></ul>
  8. 8. Network Hardware <ul><li>Switch </li></ul><ul><ul><li>Split large networks into small segments, decreasing the number of users sharing the same network resources and bandwidth. </li></ul></ul><ul><ul><li>Understands when two devices want to talk to each other, and gives them a switched connection </li></ul></ul><ul><ul><li>Helps prevent data collisions and reduces network congestion, increasing network performance. </li></ul></ul><ul><ul><li>Most home users get very little, if any, advantage from switches, even when sharing a broadband connection . </li></ul></ul>
  9. 9. Network Hardware <ul><li>Bridge </li></ul><ul><ul><li>Connects two LANs and forwards or filters data packets between them. </li></ul></ul><ul><ul><li>Creates an extended network in which any two workstations on the linked LANs can share data. </li></ul></ul><ul><ul><li>Transparent to protocols and to higher level devices like routers. </li></ul></ul><ul><ul><li>Forward data depending on the Hardware (MAC) address, not the Network address (IP). </li></ul></ul>
  10. 10. Network Hardware <ul><li>Repeater </li></ul><ul><ul><li>Used to boost the signal between two cable segments or wireless access points. </li></ul></ul><ul><ul><li>Can not connect different network architecture. </li></ul></ul><ul><ul><li>Does not simply amplify the signal, it regenerates the packets and retimes them. </li></ul></ul>
  11. 11. Network Hardware <ul><li>Router </li></ul><ul><ul><li>A device that connects LANs. </li></ul></ul><ul><ul><li>Uses standardized protocols to move packets efficiently to their destination. </li></ul></ul><ul><ul><li>More sophisticated than bridges, connecting networks of different types (for example, star and token ring) </li></ul></ul><ul><ul><li>Forwards data depending on the Network address (IP), not the Hardware (MAC) address . </li></ul></ul><ul><ul><li>Routers are the only one of these four devices that will allow you to share a single IP address among multiple network clients. </li></ul></ul>
  12. 12. Network Hardware <ul><li>Additional Network Hardware Devices </li></ul><ul><ul><li>Network Interface Cards (NICs) </li></ul></ul><ul><ul><ul><li>Puts the data into packets and transmits packet onto the network. </li></ul></ul></ul><ul><ul><ul><li>May be wired or wireless. </li></ul></ul></ul><ul><ul><li>Gateway </li></ul></ul><ul><ul><ul><li>Connects networks with different protocols like TCP/IP network and IPX/SPX networks. </li></ul></ul></ul><ul><ul><ul><li>Routers and Gateways often refer to the same device. </li></ul></ul></ul><ul><ul><li>Proxy server </li></ul></ul><ul><ul><ul><li>Isolates internal network computers from the internet. </li></ul></ul></ul><ul><ul><ul><li>The user first access the proxy server and the proxy server accesses the internet and retrieves the requested web page or document. The user then gets a copy of that page from the proxy server. </li></ul></ul></ul>
  13. 13. Common Network Media <ul><li>Electrical (copper) </li></ul><ul><ul><li>Coaxial Cable </li></ul></ul><ul><ul><ul><li>Single copper conductor in the center surrounded by a plastic layer </li></ul></ul></ul><ul><ul><ul><li>for insulation and a braided metal outer shield. </li></ul></ul></ul><ul><ul><li>Twisted pair </li></ul></ul><ul><ul><ul><li>Four pairs of wires twisted to certain specifications. </li></ul></ul></ul><ul><ul><ul><li>Available in shielded and unshielded versions. </li></ul></ul></ul><ul><ul><li>Fiber-optic </li></ul></ul><ul><ul><ul><li>A cable, consisting of a center glass core surrounded by layers of </li></ul></ul></ul><ul><ul><li> plastic, that transmits data using light rather than electricity. </li></ul></ul><ul><li>Atmosphere/Wireless – Uses Electromagnetic waves. whose frequency </li></ul><ul><ul><li>Range is above that of microwaves, but below that of the visible spectrum. </li></ul></ul><ul><ul><li>Choose Media based on : </li></ul></ul><ul><ul><li>Wiring configurations </li></ul></ul><ul><ul><li>Distance and location limitations </li></ul></ul><ul><ul><li>Speed </li></ul></ul><ul><ul><li>Reliability </li></ul></ul><ul><ul><li>Security </li></ul></ul><ul><ul><li>Budget </li></ul></ul>
  14. 14. Copper - Twisted Pair <ul><li>Dialup over telephone line. </li></ul><ul><ul><li>DSL (Digital Subscriber Line) </li></ul></ul><ul><ul><ul><li>High-speed (256 Kbps – 55 Mbps), Full-duplex. </li></ul></ul></ul><ul><ul><ul><li>Asymmetric Digital Subscriber Line (ADSL) and </li></ul></ul></ul><ul><ul><ul><li>High-bit-rate Digital Subscriber Line (HDSL) </li></ul></ul></ul><ul><li>Connector </li></ul><ul><ul><ul><li>RJ-45 - Standard connectors used for unshielded twisted -pair cable. </li></ul></ul></ul>
  15. 15. Ethernet Specifications <ul><li>10BaseT </li></ul><ul><ul><li>Ethernet specification for unshielded twisted pair cable (category 3, 4, or 5), transmits signals at 10 Mbps (megabits per second) with a distance limit of 100 meters per segment. </li></ul></ul><ul><li>10BaseF </li></ul><ul><ul><li>Ethernet specification for fiber optic cable, transmits signals at 10 Mbps (megabits per second) with a distance limit of 2000 meters per segment. </li></ul></ul><ul><li>100BaseT </li></ul><ul><ul><li>Ethernet specification for unshielded twisted pair cabling that is used to transmit data at 100 Mbps (megabits per second) with a distance limit of 100 meters per segment. </li></ul></ul><ul><li>1000BaseTX </li></ul><ul><ul><li>Ethernet specification for unshielded twisted pair cabling that is used to transmit data at 1 Gbps (gigabits per second) with a distance limitation of 220 meters per segment. </li></ul></ul>
  17. 17. <ul><li>Infrared light is transmitted through fiber and confined due to total internal reflection. </li></ul><ul><li>Fibers can be made out of either plastic or glass. </li></ul><ul><li>Used for high speed backbones and pipes over long distances. </li></ul><ul><li>Comparatively expensive. </li></ul>Optical Fiber
  18. 19. Sample LAN Implementation Home Configuration
  19. 20. Sample LAN Implementation Business Configuration
  20. 21. Sample LAN Implementation Business Configuration
  21. 22. Telecommunication And Network Technology
  22. 23. What is a topology? <ul><li>A topology refers to the manner in which the cable is run to individual workstations on the network. The dictionary defines topology as: the configurations formed by the connections between devices on a local area network (LAN) or between two or more LANs. There are three basic network topologies (not counting variations thereon): the bus, the star, and the ring. </li></ul><ul><li>It is important to make a distinction between a topology and an architecture. A topology is concerned with the physical arrangement of the network components. In contrast, an architecture addresses the components themselves and how a system is structured (cable access methods, lower level protocols, topology, etc.). An example of an architecture is 10baseT Ethernet which typically uses the start topology. </li></ul>
  23. 24. <ul><li>The hub offers a common connection for all stations on the network. Each station has its own direct cable connection to the hub. In most cases, this means more cable is required than for a bus topology. However, this makes adding or moving computers a relatively easy task; simply plug them into a cable outlet on the wall. </li></ul><ul><li>If a cable is cut, it only affects the computer that was attached to it. This eliminates the single point of failure problem associated with the bus topology. (Unless, of course, the hub itself goes down.) </li></ul>What is a star topology?
  24. 25. HOST A Star Network Network Topologies
  25. 26. HUB A Star Network Network Topologies
  26. 27. A Star Network Network Topologies
  27. 28. A Star Network Pros Cons Easy to add & remove items Ease of network monitoring and mgt Network not susceptible to single machine failure Susceptible to central hub Difficult installation / wire requirements Network Topologies
  28. 29. What is a ring topology? <ul><li>A ring topology consists of a set of stations connected serially by cable. In other words, it’s a circle or ring of computers. There are no terminated ends to the cable; the signal travels around the circle in a clockwise direction. </li></ul><ul><li>Note that while this topology functions logically as ring, it is physically wired as a star. The central connector is not called a hub but a Multistation Access Unit or MAU . Under the ring concept, a signal is transferred sequentially via a &quot;token&quot; from one station to the next. When a station wants to transmit, it &quot;grabs&quot; the token, attaches data and an address to it, and then sends it around the ring. The token travels along the ring until it reaches the destination address. The receiving computer acknowledges receipt with a return message to the sender. The sender then releases the token for use by another computer. </li></ul><ul><li>Each station on the ring has equal access but only one station can talk at a time. </li></ul><ul><li>In contrast to the ‘passive’ topology of the bus, the ring employs an ‘ active’ topology. Each station repeats or ’boosts’ the signal before passing it on to the next station. Rings are normally implemented using twisted pair or fiber-optic cable. </li></ul>
  29. 30. A Ring Network Network Topologies
  30. 31. A Ring Network Network Topologies
  31. 32. A Ring Network Network Topologies
  32. 33. A Ring Network Pros Cons Equal network access by all machines Even network performance regardless of number of users Susceptible to single computer failure Difficult to isolate network problems Difficulty of adding or removing computers Network Topologies
  33. 34. What is a bus topology? <ul><li>A bus topology connects each computer (node) to a single segment trunk. A ‘ trunk ’ is a communication line, typically coax cable, that is referred to as the ‘bus .’  The signal travels from one end of the bus to the other. A terminator is required at each end to absorb the signal so it does not reflect back across the bus. </li></ul><ul><li>In a bus topology, signals are broadcast to all stations. Each computer checks the address on the signal (data frame) as it passes along the bus. If the signal’s address matches that of the computer, the computer processes the signal. If the address doesn’t match, the computer takes no action and the signal travels on down the bus. </li></ul><ul><li>The bus topology is passive . In other words, the computers on the bus simply ‘listen’ for a signal; they are not responsible for moving the signal along. A bus topology is normally implemented with coaxial cable </li></ul>
  34. 35. HOST A Bus Network Network Topologies
  35. 36. HOST A Bus Network Network Topologies
  36. 37. A Bus Network Network Topologies
  37. 38. <ul><li>In a regular bus , each computer is attached to the cable segment (called a backbone) by means of a drop cable (a shorter cable connecting the computer to the backbone) </li></ul><ul><li>In a local bus , each computer is attached directly to the backbone in a daisy-chain configuration by means of a &quot;T&quot; connector .  Peer-to-peer networks are often configured as a local bus. </li></ul>WHAT IS THE DIFFERENCE BETWEEN A REGULAR BUS AND A LOCAL BUS?
  38. 39. A Bus Network Pros Cons Simple & reliable Network expansion is easy & inexpensive Economical use of cable Speed susceptible to number of users Cable breaks & lack of termination can halt network Difficult to troubleshoot Network Topologies