CN2668 Routers and Switches

1. CN2668Routers and Switches Kemtis Kunanuraksapong MSIS with Distinction MCTS, MCDST, MCP, A+

2. Agenda • Chapter 2: Network Devices • Exercise • Quiz

3. Repeaters • Attenuation • Degradation of signal clarity • Repeats every signal, 0 or 1 • Function at Layer 1 • If the network use the same data type and packet structure, a repeater can be used as a connection device. (twisted-pair cable and coaxial)

4. Hubs • Active hub • The hub that repeat AND amplify signal • Passive hub • Merely connects cables to form a network • Often form a Star Topology; see Figure 2-3 on Page 27

5. Summary of Repeaters / Hubs • Advantages • Extend a network’s total distance • Do not serious affect network performance • Disadvantages • Cannot connect different network architectures such as Token ring and Ethernet • Do not reduce network traffic • Do not segment the network

6. Wireless Access Points • Standards and Organization • 802.11a/b/g/n • See Table 2-1 on Page 29 • All the devices share the same bandwidth • Two modes • Ad hoc mode • Basic service set (BSS) / Extended Service Set (ESS)

7. Wireless Access Points • Service Set Identifier (SSID) • Broadcast / Hide • Wireless Security Measures • 802.1x • Function at layer 1 • Extensible Authentication Protocol (EAP) • Function at layer 2

8. Wireless Access Points • 802.11 Security options • WEP (Wired Equivalent Privacy) • WPA (Wi-Fi Protected Access) • WPA2 • 802.11i • See Table 2-2 on Page 31

9. Wireless Access Points • Troubleshooting • Make sure your wired LAN is working • Complete a wireless site survey to determine access point placement • Install the access point(s) with no security • Attempt to associate to the access point with a laptop • Configure security on both the access point and the client • Verify connectivity at all layers

10. Wireless Access Points • Possible degradation of wireless signal • Interference from too much overlap of one access point’s cell range onto another • Incompatible 802.11 standard (a/b/g/n) • Antennas is not securely connected and in optimal position • Sources of interference such as large bodies of water, metal building, cordless phone, etc.

11. Summary of WAP • Advantages • Provide mobility • Extend the range of the network without running additional wires • Disadvantages • Security concerns • Provide less bandwidth than wired devices

12. Network Segmentation • To segment the network into smaller collision domain • Bandwidth are shared among all nodes, hence segmentation improve the bandwidth • See Figure 2-5 on Page 33 • Bridges • Switches • Routers

13. Bridges • Layer 2 device • Filter traffic between segments by examining the destination MAC address • Map MAC addresses to bridge segment • Forwards / drops the frame • If broadcast frame has been sent, the bridge will forward to every node except the sender

14. Bridges • Transparent Bridges • Build the MAC table as they receive frames • Source-Routing Bridges • Rely on the source of the frame transmission to provide the routing information • The source determines the best path by sending out explorer frames • The destination determines best routes and response back

15. Bridges • Translation Bridges • Can connect networks with different architecture • Act as transparent bridges to Ethernet host • Act as source-routing bridges to Token Ring host

16. Summary of Bridges • Advantages • Extend a network by acting as a repeater • Reduce network traffic on a segment by subdividing network communications • Increase available bandwidth • Reduce collisions • Disadvantages • Slower than and more expensive than repeaters and hubs • Does not filter broadcast traffic

17. Switches • Function at Layer 2 • Reduces the number of frames transmitted • Virtual circuit • A connection between source and destination • Filters based on MAC addresses and mapped to port

18. Summary of Switches • Advantages • Increase available bandwidth • Reduce collisions • Disadvantages • More expensive • Broadcast traffic maybe troublesome

19. Routers • Operates the same way as bridges and switches • Use the logical address (IP address) at Layer 3 • Every interface represents a different network • Create collision domains as well as broadcast domains

20. Summary of Routers • Advantages • Connect different network architectures • Choose the best path using dynamic routing • Reduce traffic by creating collisions and broadcast domains • Disadvantages • Work only with routable network protocols • Dynamic router communication cause additional overhead • Slower than others since the packet must be analyzed from layer 1 to 3

21. Brouters • A bridge + router • Can route both routable and nonroutable protocol • Can operate on both layer 2 and 3

22. Gateway • To translate between different protocol suites • Create the most latency • It convert the packet to another format

23. Ethernet Operations • IEEE 802.3 • Carrier Sense Multiple Access with Collision Detection (CSMA/CD) • After sending packet, they have to wait 9.6 microseconds (Interframe gap IFG or Interpacket gap IPG) • Collisions • When packet sent, there will be carrier signal • If two host send out at the same time, one of them will send 32-bit jam signal

24. Ethernet Operations • Fast Ethernet (100BaseT) • 100 Mbps • IEEE 802.3u • Gigabit Ethernet (1000BaseX) • 1000 Mbps • IEEE 802.3ab

25. Ethernet Operations • Half- and Full-Duplex Communications • Telephone • Walkie-talkie • Smoke

26. Assignment • Review Questions • 1 – 28 • Case Projects • 4, 5