1. Switching ดร. อนันต์ ผลเพิ่ม Anan Phonphoem, Ph.D. anan@cpe.ku.ac.th http://www.cpe.ku.ac.th/~anan Computer Engineering Department Kasetsart University, Bangkok, Thailand

2. 2 Switching Point-to-point connection (Mesh) wasteful Multipoint connection (Bus) Distance (collision Domain) Number of devices Switch

3. 3 Switched Network

4. Switching Methods Circuit switchingMessage switchingPacket switching

5. 5 Circuit switched network

6. 6 Switch Creates a temporary connection between input/output

7. 7 A folded switch

8. Switching Methods Circuit switchingMessage switchingPacket switching Space-divisionTime-division

9. 9 Space-Division Switches: Crossbar Switches Using electronic micro-switches (transistors) Low efficiency (<25% use)

10. 10 Multistage Switch More efficiency Blocking

11. 11 Switching path Also provide multiple paths

12. Switching Methods Circuit switchingMessage switchingPacket switching Space-divisionTime-division

13. 13 TDM Time-slot interchange (TSI)

14. 14 Time-slot interchange

15. 15 Space VS. Time-Division Space-division switching + Instantaneous - # of cross points Time-division switching + No cross point - Create delay

16. 16 Time-space-time (TST) switch Other combinations: TSST, STTS, etc.

17. Switching Methods Circuit switchingMessage switchingPacket switching DatagramVirtual circuit SVCPVC

18. 18 Circuit switching weakness Design for voice (telephone) Non-voice transmission is bursty Data rate Assume a single data rate for both ends Inflexibility Same path (no adaptation)

19. 19 Datagram approach Each packet is treated independently Packet is called Datagram

20. 20 Multiple channels in datagram approach A  X B  Y B

21. Switching Methods Circuit switchingMessage switchingPacket switching DatagramVirtual circuit SVCPVC

22. 22 Virtual Circuit Same route – choose at start PVC (Permanent VC) Leased Line SVC (Switched VC) Dial-up

23. 23 Switched virtual circuit (SVC)

24. 24 Switched virtual circuit (SVC)

25. 25 Switched virtual circuit (SVC)

26. 26 Circuit-switched VS. Virtual-circuit connection Path VS. route Dedicated VS. sharing Circuit-switched connectionVirtual-circuit connection

27. 27 Virtual Circuit in WAN

28. 28 VCI

29. 29 VCI Phases

30. 30 Switching

31. 31 Source-to-destination data transfer

32. 32 SVC setup request

33. 33 SVC setup acknowledgment

34. Switching Methods Circuit switchingMessage switchingPacket switching

35. 35 Message switching