1. 1 DQDB -  All rights reserved. No part of this publication and file may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission of Professor Nen-Fu Huang (E-mail: nfhuang@cs.nthu.edu.tw). Distributed Queue Dual Bus (IEEE 802.6 DQDB)

2. 2 DQDB - DQDB Network Structure

3. 3 DQDB - DQDB Application: As A Backbone Network

4. 4 DQDB - DQDB Based Metropolitan Area Networks

5. 5 DQDB - DQDB Node Structure

6. 6 DQDB - DQDB Access Structure (Or-Write Circuit)

7. 7 DQDB - Looped Bus Structure of a DQDB Network

8. 8 DQDB - Network Reconfiguration Examples

9. 9 DQDB - Slot Structure (Fixed Length, 53 Octets)

10. Queued-Arbitraed (QA) Access Method  l Busy Bit  l Request Bit

11. 11 DQDB - Queued-Arbitrated (QA) Slot Access  When a node does not have a QA segment to send on Bus A

12. 12 DQDB - Queued-Arbitrated (QA) Slot Access  When a node does have a QA segment to send on Bus A

13. 13 DQDB - QA Access Operation Example  A sub-network consisting of five nodes queuing for access  RQ: Request Counter  CD : Countdown Counter  All slots passing on bus A are busy  Nodes 5, 2, and 3 queue for access in that order

14. 14 DQDB - QA Access Operation Example

15. 15 DQDB - QA Access Operation Example

16. 16 DQDB - MAC Connectionless Service PDU

17. 17 DQDB - Segmentation of an IMPDU into DMPDUs

18. 18 DQDB - DMPDU to Slot

19. 19 DQDB - MID Page Allocation Protocol

20. 20 DQDB - MID Page Allocation Protocol

21. 21 DQDB - Address Format

22. 22 DQDB - Isochronous Channel Concepts and PA Slot Format

23. 23 DQDB - Isochronous Channels Examples

24. 24 DQDB - Isochronous Channels Examples

25. 25 DQDB - Establishment of Isochronous Channels

26. 26 DQDB - Layer Management Message Flows at the Originating Site

27. 27 DQDB - Layer Management Message Flows at the Originating Site

28. 28 DQDB - Layer Management Message Flows at the Originating Site

29. 29 DQDB - DQDB Access Method Characteristics  Provides two modes of access:  Non-Arbitrated Access (Pre-Arbitrated, PA)  Queued-Arbitrated Access (QA)  PA access supports Isochronous connection-oriented services  QA access supports Asynchronous services  QA access supports three priority levels  QA access provides low access delays at low subnetwork loading and little wasted capacity at high loading  The relative throughput that can be supported by QA access is independent of sub-network size or bit rate  Operates as a network in a size of 50km (diameter)  Slotted structure compatible with broadband-ISDN