1. CS 447 Networks and Data Communication Department of Computer Science Southern Illinois University Edwardsville Fall, 2013 Dr. Hiroshi Fujinoki E-mail: hfujino@siue.edu Local-Area-Network (LAN) Architecture

2. LAN_Architecture/001 Three major LAN architectures 1. Bus Topology LAN 2. Ring Topology LAN 3. Star Topology LAN Most popular topology today CS 447 Networks and Data Communication

3. LAN_Architecture/002 1. Bus Topology LAN  Data will be transmitted by a physically shared cable  Data will be broadcast (delivered to every host in a LAN) Segment Terminator Shared transmission medium (= bus) Host Properties LAN Segment  The only network where host computers can be directly connected CS 447 Networks and Data Communication

4. LAN_Architecture/003 2. Ring Topology LAN Data will be first transmitted to a tapping repeater. A tapping repeater inserts data (packet) into a ring Tapping Repeater Every tapping repeater receives and forwards packets The owner repeater needs to remove packets from a ring Properties CS 447 Networks and Data Communication

5. LAN_Architecture/004 3. Star Topology LAN Every host is directly connected to a hub Bus-based Hub/Switching Hub Properties Hosts are not directly connected to other hosts CS 447 Networks and Data Communication

6. LAN_Architecture/005 3. Star Topology LAN (continued) Low cost Limited throughput Bus-based hub (internal shared bus) internal shared bus Properties It is essentially Bus topology LAN CS 447 Networks and Data Communication

7. LAN_Architecture/006 3. Star Topology LAN (continued) High cost Better throughput than bus-based hub Switching Hub Non-broadcasting (better security) Switching Fabric Properties A BC D If A  B C  D CS 447 Networks and Data Communication

8. LAN_Architecture/007 Connecting Devices in LAN Bridge Router Hub Repeater Low level High level CS 447 Networks and Data Communication

9. LAN_Architecture/007 CS 447 Networks and Data Communication Repeaters Two-Port Repeaters Repeater Hubs

10. LAN_Architecture/007 CS 447 Networks and Data Communication Switches (AKA “Bridges”)

11. LAN_Architecture/007 CS 447 Networks and Data Communication Routers

12. LAN_Architecture/008 Repeater = signal re-former (+amplifier) Input (segment 1) Output (segment 2) Repeater LAN Segment 2 LAN Segment 1 Repeater One LAN segment Signal with noise Clean signal CS 447 Networks and Data Communication

13. Hub LAN_Architecture/009 2. Hub = a multi-port repeater Ports Internal shared bus Repeater Broadcast messages go through a hub (or Repeater) CS 447 Networks and Data Communication

14. LAN_Architecture/010 3. Bridge = a packet localizer (packet filter) LAN 1 LAN 2 ABC XYZ 1 2 Bridge HOST PORT A B C X Y Z 1 1 1 2 2 2 CS 447 Networks and Data Communication

15. LAN_Architecture/011 LAN 1 LAN 2 ABC XYZ 1 2 Bridge (1) if A sends data to B The bridge will NOT forward packet to LAN2 HOST PORT A B C X Y Z 2 2 2 1 1 1 A tries to send data to Host B CS 447 Networks and Data Communication

16. LAN_Architecture/012 LAN 1 LAN 2 ABC XYZ 1 2 Bridge (2) if A sends data to Y The bridge will forward the packet to LAN2 A tries to send data to Host Y HOST PORT A B C X Y Z 2 2 2 1 1 1 CS 447 Networks and Data Communication

17. LAN_Architecture/013 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. CS 447 Networks and Data Communication

18. LAN_Architecture/014 3. Bridge = a packet localizer (packet filter) LAN 1 LAN 2 ABC XYZ 1 2 Bridge HOST PORT A B C X Y Z 1 2 A C Data Origin Destination A C Data A Z A Z Origin Destination CS 447 Networks and Data Communication

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

20. Receiver Sender LAN_Architecture/016 4. Router = intelligent packet forwarding device between two network domains Routers exchange routing tables Router Network D Network C Network (= LAN or WAN) A Network B Internet CS 447 Networks and Data Communication