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LAN Technology

TK3133 Computer Network Technology. LAN Technology. Introduction. LAN concept and technology Importance of sharing in LAN Basic Network topology Hardware addressing and frame type identification. Network Category. Network connection type : Point to Point or Mesh network

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LAN Technology

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  1. TK3133 Computer Network Technology LAN Technology

  2. Introduction • LAN concept and technology • Importance of sharing in LAN • Basic Network topology • Hardware addressing and frame type identification

  3. Network Category • Network connection type : • Point to Point or Mesh network • Sharing communication lines

  4. Point to point communication • Original line configuration communication system • Computer connected to Communication lines with each connected to two computers in forming mesh network or point to point • Allow flexibility in hardware communication, packet formatting and etc. • Provide security since communication lines are not shared

  5. Point to point connection • Number of wires increase when number of computer increases • Exp: 2,3,4 computer connection

  6. Point to point connection • Adding a computer (Nth computer) require N-1 new connections • Number of connection = (N2 – N)/2 • Limitation : expensive and too many lines

  7. Sharing communication channels • Differ with long distance network • Prevent weaknesses in point to point : expensive, dedicated and overlapping • Introducing LAN – sharing a communication channel (cable) by several computers

  8. LAN • Reducing number of communication channels • LAN developed in early 1970 • Main idea – reducing number of channels by sharing connection among computers • But not suitable for long distance because of the coordination problem

  9. LAN • LAN technology reducing the cost by reducing number of connection • But connected computers have to compete for using shared connection • Using principle of locality of reference to acquire computer communication pattern.

  10. Broadcasting network • LAN is a broadcasting network • Data packet that sent by a station will be transmitted to all stations • LAN topology • Network can be categorized according to the shape • 3 popular topologies • Star, ring and bus

  11. Star topology • All computers are connected to a middle point called hub • Hub as device receives data packet and send it to destination

  12. Star topology • In practice, cable fixing can be parallel (or not) with computer

  13. Star topology • consequence :-

  14. Ring topology • Computers are connected in closed coil. • First host will send data to the second host . Second host will send the data to the third host and so is for subsequent host. • Short connection cable from computer to the ring

  15. Ring topology • A computer connected to another two computers.

  16. Bus topology • A cable connected to all computers • A computer has a connector to the shared cable • Computers should synchronized and allow only a computer send data at a time.

  17. Bus topology • A cable connected to many computers

  18. Various topology • Each topology has its own advantages and disadvantages • Selection depends on wiring schema

  19. Exp. of LAN Bus- Ethernet • Ethernet is the most popular LAN network access control • Developed by Xerox in the middle of 70s – maintain by IEEE • Using bus topology • A cable • Connect various computers

  20. LAN- Ethernet • A Ethernet cable is called segment • Up to 500m lenght • Transmission rate is 10Mbps, 100Mbps (Fast Ethernet) and 1Gbps (Gigabit Ethernet) • Using Manchester encoding signal modulation

  21. Manchester encoding (a) Binary encoding, (b) Manchester encoding, (c) Differential Manchester encoding.

  22. LAN- Ethernet operation • A computer send data at a time • Signal is modulated carrier that transmitted from sender into two direction along the segment

  23. Carrier Sense Multiple Access with Collision Detection CSMA/CD • There in no central control management when computer send to ether • use CSMA to coordinate transmission among connected computers • Carrier sense: station listen to channel before sending • Collision Detection: station can decide whether there is frame clash through listening to the channel while transmitting

  24. CSMA/CD - IEEE 802.3 • 802.3 standard • 802.3 basic is 10-Mbps “Ethernet”

  25. Wireless LAN 802.11 and CSMA/CA • Operating at 11Mbps using frequency in domain 2.4 GHz • Avoiding clash by using CSMA with Collision Avoidance

  26. LocalTalk • LAN technology that use bus topology • Interface include Macintosh computer • Low-cost, easy to fix and connect • use CSMA/CD

  27. Token Bus - IEEE 802.4 • Disadvantage because there is clash – Choose a technique that avoid clash • Token concept – bus and ring • Only sender that receives token is allowed to send frame • After sending, pass the token

  28. Token Bus • Fix the whose turn after this to receive the token for equal access

  29. Token Ring- IEEE 802.5 (IBM Token Ring) • Operating at 4 and 16 Mbps • No bus, only nodes and lines • Use token transmission to synchronize access to the ring • Each node sends frame following clock rotation by getting the token first

  30. FDDI • Fiber Distributed Data Interconnect (FDDI) is a ring technology • use fiber optic between station • Tansmission at the rate of 100Mbps • Use a pair of fiber to create two coils with a centre • As a back-up if there is any damage

  31. FDDI • Using flow in two direction

  32. ATM – Star network • Asynchronous Transfer Mode technology that contain packet switch that connect to computers • ATM switch form hub in which computer connected in star topology • data from sender flow thorough switch to destinations

  33. ATM – Star Network • Transmission rate is over 100Mbps • using fiber optic to connect computer to switch • Each connection has 2 fiber

  34. Communication in LAN • Technique how to send message through LAN medium to specific computer destination • Sender computer uses hardware address in frame to identify direction to destination • Sender also identify type of data that brought in the frame

  35. Identify destination • Data is sent through the shared network reach all computers that connected to it • Hardware interface trace the frame sent and extract frame from medium • But many application only want data to be sent to destination and not all computers

  36. Hardware addressing • Many network technology has a hardware addressing schema that identify particular station or computer • Each station is assigned to a numeric hardware address or unique physical address • Sender will insert hardware address to each frame that sent from source and destination. • Only station that recognized from frame receive copy of the frame

  37. LAN hardware and packet filtering • LAN Hardware Organization and computer

  38. Hardware address Format • numeric value • Size is selected according to specific network technology • Length is from 1 to 6 bytes • unique in a LAN • static, dynamic and configurable

  39. Frame Format and Frame Head • LAN standard technology define frame format according to the network technology\ • general format : • Head has address and additional information (in fixed size field). • Data area can be in various size

  40. Example of frame format • Ethernet frame format

  41. Part 2- Introduction • Interface card • Why need different card • What is transceiver? • LAN wired schema • Logical and physical topology • How to improve LAN?

  42. LAN speed and computer • data transmission speed of LAN is faster compared to CPU • LAN speed is not dependent to any processor speed • Allow mix system on it • New computer can be connected without influencing LAN speed

  43. Network hardware interface • Computer uses special hardware to network connection • Network Interface card (NIC) that understand electrical signal use on network, rate in which the data received and sent as well as frame detail • Connector to computer receive cable to be connected to physical network

  44. NIC and network hardware • NIC is built for only one type of physical network • Ethernet interface cannot be used with Token Ring • However, certain NIC can be used with other hardware similar to • thick, thin and 10BaseT Ethernet • 10Mbps and 100Mbps Ethernet

  45. Connection between NIC and physical network • 2 methods :- • NIC is directly connected to medium • Cable from NIC connect to additional circuit that connected to medium • Ethernet wiring method • Standard 10Base5 • standard 10Base2 • standard 10BaseT

  46. Connection between NIC and physical network

  47. 10Base5 - Thick Ethernet • Use ether cable • AUI cable (drop cable) from NIC to transceiver • AUI cable carry digital signal from NIC to transceiver • Transceiver generate analog signal to ether cable

  48. 10Base5 - Thick Ethernet • A AUI cable connected computer to transceiver

  49. 10Base5

  50. 10Base5 Transceiver

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