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CS 447 Networks and Data Communication

Understand local area network architectures with bus, ring, and star topologies. Learn about hubs, repeaters, switches, bridges, and routers in LAN setups. Study packet forwarding, switching tables, and host address learning algorithms in LAN design.

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CS 447 Networks and Data Communication

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  1. Local-Area-Network (LAN) Architecture CS 447 Networks and Data Communication Department of Computer Science Southern Illinois University Edwardsville Fall, 2019 Dr. Hiroshi Fujinoki E-mail: hfujino@siue.edu

  2. CS 447 Networks and Data Communication Local Area Networks (LAN’s)  The networks that provide “direct connectivity” to terminal host computers  Each LAN segment covers terminal host computers within 200~300 feet Gateway Router INTERNET up to 300 feet (image source: http://digestwebdesign.com/what_is_internet.html) LAN_Architecture/001

  3. CS 447 Networks and Data Communication Local Area Networks (LAN’s) LAN_Architecture/002

  4. Most popular topology today CS 447 Networks and Data Communication Three major LAN architectures 1. Bus Topology LAN 2. Ring Topology LAN 3. Star Topology LAN LAN_Architecture/003

  5. Host Host Host Host Shared transmission medium (= bus) Segment Terminator LAN Segment Properties CS 447 Networks and Data Communication 1. Bus Topology LAN  Data will be transmitted by a physically shared cable  Data will bebroadcast(delivered to every host in a LAN)  The only network where host computers can be directly connected LAN_Architecture/004

  6. Tapping Repeater Properties CS 447 Networks and Data Communication 2. Ring Topology LAN • Data will be first transmitted to a tapping repeater. • A tapping repeater inserts data (packet) into a ring • Every tapping repeater receives and forwards packets • The owner repeater needs to remove packets from a ring LAN_Architecture/005

  7. Bus-based Hub/Switching Hub Properties CS 447 Networks and Data Communication 3. Star Topology LAN • Every host is directly connected to a hub • Hosts are not directly connected to other hosts LAN_Architecture/006

  8. internal shared bus Properties CS 447 Networks and Data Communication 3. Star Topology LAN (continued) Bus-based hub (internal shared bus) • It is essentially Bus topology LAN • Limited throughput • Low cost LAN_Architecture/007

  9. Switching Fabric If A  B C  D A B C D Properties CS 447 Networks and Data Communication 3. Star Topology LAN (continued) Switching Hub • Better throughput than bus-based hub • Non-broadcasting (better security) • High cost LAN_Architecture/008

  10. Repeater Low level • Hub • Bridge • Router High level CS 447 Networks and Data Communication Connecting Devices in LAN LAN_Architecture/009

  11. CS 447 Networks and Data Communication Switches (AKA “Bridges”) LAN_Architecture/011

  12. CS 447 Networks and Data Communication Routers LAN_Architecture/012

  13. LAN Segment 1 LAN Segment 2 Repeater One LAN segment Clean signal Signal with noise Repeater CS 447 Networks and Data Communication Repeater = signal re-former (+amplifier) Output (segment 2) Input (segment 1) LAN_Architecture/013

  14. Internal shared bus Hub Ports Broadcast messages go through a hub (or Repeater) Repeater CS 447 Networks and Data Communication 2. Hub = a multi-port repeater LAN_Architecture/014

  15. PORT HOST A 1 B 1 1 C A X B Y C Z X 2 2 Y 2 Z CS 447 Networks and Data Communication 3. Bridge = a packet localizer (packet filter) Bridge 1 2 LAN 1 LAN 2 LAN_Architecture/015

  16. PORT HOST A 1 A tries to send data to Host B B 1 1 C X A B Y Z C X 2 2 Y 2 Z The bridge will NOT forward packet to LAN2 CS 447 Networks and Data Communication (1) if A sends data to B Bridge 1 2 LAN 1 LAN 2 LAN_Architecture/016

  17. PORT HOST A 1 A tries to send data to Host Y B 1 The bridge will forward the packet to LAN2 1 C X A Y B Z C X 2 2 Y 2 Z CS 447 Networks and Data Communication (2) if A sends data to Y Bridge 1 2 LAN 1 LAN 2 LAN_Architecture/017

  18. CS 447 Networks and Data Communication Host address learning algorithm (1) Bridge receives a packet at one of its ports (2) Check the port table for the destination of the packet (3) If the destination host does not appear in the table, transmit the packet to all the ports except the one where the packet was received. Record the origin of the packet. Then, terminate the learning algorithm. (4) If the destination host appears in the table, check the destination port. If the destination port is the one where the packet arrives, do nothing. Otherwise, forward the packet to the destination port. LAN_Architecture/018

  19. PORT HOST A A A C C Data Data B Origin A A Z Z C Origin Destination A X Y B C Z X Destination Y Z Data Data CS 447 Networks and Data Communication 3. Bridge = a packet localizer (packet filter) Bridge 1 2 LAN 1 LAN 2 1 2 LAN_Architecture/019 Switching Table

  20. PORT HOST A B Origin Z Z X X C Destination A X Y B C Z X Y Z Data Data CS 447 Networks and Data Communication 3. Bridge = a packet localizer (packet filter) Bridge 1 2 LAN 1 LAN 2 1 2 2 LAN_Architecture/020 Switching Table

  21. Sender Network (= LAN or WAN) A Routers exchange routing tables Router Network B Network D Internet Network C Receiver CS 447 Networks and Data Communication 4. Router = intelligent packet forwarding device between two network domains LAN_Architecture/021

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