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乙太被動式光學網路上離線排程 機制之設計

Speaker: 尹培華 Advisor: 吳和庭 教授 日期 :2011/07/27. 乙太被動式光學網路上離線排程 機制之設計. Motivation 乙太被動式光學網路 EPON Architecture 多點控制協定 MPCP 動態頻寬分配機制 Dynamic Bandwidth Allocation 線上排程 Online Scheduling IPACT(Interleaved Polling with Adaptive Cycle Time ) 離線排程 Offline Scheduling. Outline.

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乙太被動式光學網路上離線排程 機制之設計

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  1. Speaker:尹培華 Advisor:吳和庭 教授 日期:2011/07/27 乙太被動式光學網路上離線排程機制之設計

  2. Motivation • 乙太被動式光學網路EPON • Architecture • 多點控制協定MPCP • 動態頻寬分配機制Dynamic Bandwidth Allocation • 線上排程Online Scheduling IPACT(Interleaved Polling with Adaptive Cycle Time ) • 離線排程Offline Scheduling Outline

  3. 離線排程Offline Scheduling Offline Scheduling DBA Mechanism (Offline-DBA) Offline Scheduling with Early Allocation Scheme(Early-DBA) Enhanced Offline Scheduling Mechanism(Enhanced-DBA) • 模擬結果 • 結論及未來發展 • 參考文獻 • Q&A • 附錄 Outline

  4. 癥結點 • 如何解決接取式網路和骨幹網路間所存在的傳輸瓶頸,提供用戶端更便宜、及更大量的頻寬? 解決方案 • 被動式光學網路PON(Passive Optical network)具有傳輸距離長、高頻寬等優點,因此被視為良好的解決方案。 Motivation

  5. TDM-EPON具有建置容易的優點,但是OLT和ONU間存在同步的問題,而且多個ONU間共用一個上傳通道來上傳資料,也會有資料碰撞的情形發生。TDM-EPON具有建置容易的優點,但是OLT和ONU間存在同步的問題,而且多個ONU間共用一個上傳通道來上傳資料,也會有資料碰撞的情形發生。 • 所以如何設計一個好的動態頻寬配置機制來達到有效的資料傳輸,就成了本篇研究的動機。 Motivation

  6. EPON的全名為Ethernet Passive Optical Network 乙太被動式光學網路。 • IEEE成立802.3EFM小組來制定與EPON相關的協定;詳細標準可見802.3ah。 • 主要的優勢在於可以與舊有的乙太網路架構相容,大大的降低了建置成本 EPON

  7. EPON-Architecture

  8. EPON系統資料上傳的運作模式 EPON-Overview

  9. EPON系統資料下載的運作模式 EPON-Overview

  10. MPCP的全名是Multi Point Control Protocol,多點控制協定,讓OLT和ONU間可以達成點對多點、或多點對點的有效傳輸。 • MPCP共有有五種控制訊息,負責兩種不同運作模式 • Auto-Discovery Mode • Normal Mode MPCP

  11. MPCP-GATE Message Formant

  12. MPCP-REPORT Message Formant

  13. 線上排程(Online Scheduling)

  14. Poll and stop mechanism IPACT

  15. IPACT(Interleaved Polling with Adaptive Cycle Time) IPACT

  16. 傳送視窗Transmission Window : 類似分配time slot的概念,將time slot換算成資料量的大小(Byte) , OLT利用傳送視窗來告訴ONU可以傳送的資料量大小。 • Maximum Transmission Window : 是一個threshold ,用來決定每個ONU在一個cycle 裡最多可以上傳多少資料。 Transmission Window

  17. Maximum Transmission Window Size Transmission Window

  18. 決定Transmission window大小的方式 • Limited Service Transmission Window

  19. 離線排程(Offline Scheduling)

  20. Offline Scheduling Mechanism

  21. 多餘頻寬分配概念 將ONU依頻寬要求量分為兩組(兩個集合H&L),分類基準為保證頻寬值,目的在於讓頻寬要求量大的ONU可以獲得更多的頻寬。 Excess Bandwidth Assignment

  22. Offline Scheduling Mechanism-Flow Chart

  23. Offline Scheduling Mechanism-Flow Chart

  24. 系統需求假設

  25. Offline Scheduling Mechanism with Early Allocation Scheme-Flow Chart

  26. Offline Scheduling Mechanism with Early Allocation Scheme-Flow Chart

  27. Enhanced Offline Scheduling Mechanism-Flow chart

  28. Enhanced Offline Scheduling Mechanism-Flow chart

  29. 多餘頻寬分配概念/二次頻寬分配概念 以ONU為單位做考量改成以資料類型為單位做考量 • 可以用做二次頻寬分配的頻寬總量 Excess Bandwidth Assignment

  30. Excess Bandwidth Assignment-Flow Chart

  31. 當頻寬不能滿足同一個資料類型的頻寬要求時,分配時的概念一樣依每個ONU內此資料類型所提出的頻寬要求量分為兩組,目的也是為了讓此資料類型頻寬要求量較大的ONU可以獲得更多的頻寬,這時的分類基準為為二次分配保證頻寬值。當頻寬不能滿足同一個資料類型的頻寬要求時,分配時的概念一樣依每個ONU內此資料類型所提出的頻寬要求量分為兩組,目的也是為了讓此資料類型頻寬要求量較大的ONU可以獲得更多的頻寬,這時的分類基準為為二次分配保證頻寬值。 Excess Bandwidth Assignment

  32. 系統效能分析

  33. 參數列表

  34. Traffic type_1下之系統效能比較

  35. P0 Packet Delay

  36. P1 Packet Delay ONU’s offered load

  37. P2 Packet Delay ONU’s offered load

  38. P2 Packet Dropping Rate

  39. 通道使用效率 ONU’s offered load

  40. Traffic type_1下改變guard time之系統效能比較

  41. 通道使用效率

  42. 本篇論文另外還有模擬一個不同traffic input的case ,由於設計機制的關係,在效能分析時未能得到比較好的結果,依據前述效能分析後所得出的原因,設法提出改善的方式為 • 發現系統overloaded之後,更改第一次分配的頻寬保證值, 使二次分配時還有頻寬可以分配, 也確實在效能分析上有得到比較好的結果。 在Enhanced-DBA增加條件限制

  43. 將環境更改為Long-Reach PON之後,因為傳輸距離拉長,在一個cycle內所有ONU向OLT提出的資料頻寬需求增加, 導致可以拿來做二次分配的頻寬因此減少,讓效能落差更大。 延伸-將環境改為Long-Reach PON

  44. 本篇論文提出的演算法期望在系統負載很高的時候也可以使通道使用率維持在一定的比率,但在經過模擬之後發現還是有其缺失存在,將同一套演算法套用在Long-Reach PON上時可以發現落差會更為明顯 • 未來方向除了可以朝著找出修正設計的方式改進缺失邁進,也可以針對適用Long-Reach PON上的動態頻寬分配機制做更深入的套討。 Conclusion & Future Work

  45. [1] IEEE Std 802.3ah-2004, “IEEE Standard for Information technology- Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirement-Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method andPhysical Layer Specifications,” September 2004. [2] G. Kramer, B. Mukherjee, and G. Pesavento, “Interleaved Polling with Adaptive Cycle Time (IPACT): A Dynamic Bandwidth Distribution Scheme in an Optical Access Network,”PhotonicNetwork Communications, vol. 4, no. 1 pp. 89-107, January 2002. [3] G. Kramer, B. Mukherjee, S. Dixit, Y. Ye, and R. Hirth, “Supporting differentiated classes of service in Ethernet passive optical networks,”OSAJournal of Optical Networking, vol. 1, no. 8/9, pp. 280- 298, August 2002. [4]G. Kramer, Ethernet Passive Optical Networks, McGraw-Hill Professional, ISBN: 0071445625, Publication date: March 2005. 參考文獻

  46. [5] J. Zheng and H.T. Mouftah, “Media access control for Ethernet passive optical networks: an overview,”IEEE Communications Magazine, vol.43, no.2, pp.145-150 , February 2005. [6] C.M. Assi, Yinghua Ye, Sudhir Dixit, and M.A. Ali, “Dynamic bandwidth allocation for quality-of-service over Ethernet PONs ,”IEEE Journal on Selected Areas in Communications, vol.21, no.9, pp. 1467-1477, November 2003. [7] B.Chen, J.Chen, and S. He, “Efficient and Fine Scheduling Algorithm for Bandwidth Allocation in Ethernet Passive Optical Networks,” IEEE Journal of Selected Topics in Quantum Electronics, vol.12, no.4, pp. 653-660, July/August. 2006. [8] H. Song, B-W Kim, and B. Mukherjee, “Long-Reach Optical Access Networks: A Survey of Research Challenges, Demonstrations, and Bandwidth Assignment Mechanisms,” IEEE Communications Surveys & Tutorials, vol.12, no. 1, pp. 112–123 , First Quarter 2010. 參考文獻

  47. [9] B. Skubic, Chen Jiajia, J. Ahmed, Chen Biao, L. Wosinska, and B. Mukherjee,“Dynamic bandwidth allocation for long-reach PON: overcoming performance degradation,” IEEE Communications Magazine, vol.48, no.11, pp.100-108,November 2010. [10] H. Song, B-W. Kim, and B Mukherjee, “Multi-Thread Polling: A Dynamic Bandwidth Distribution Scheme in Long-Reach PON,” IEEE Journal on Selected Areas in Communications, vol. 27, no.2, pp.134-142, February 2009. [11] Ching-Hung Chang, N. M. Alvarez, P. Kourtessis, R. M. Lorenzo and J. M. Senior, “Full-Service MAC Protocol for Metro-Reach GPONs,” IEEE Journal of Lightwave Technology, vol. 28, no. 7, pp. 1016- 1022, April 2010.  [12] Chun-Hung Chen, Ho-Ting Wu, and Kai-Wei Ke, “Predictive Credit Based Dynamic Bandwidth Allocation Mechanisms in Ethernet Passive Optical Network,” TENCON 2006. 2006 IEEE Region 10 Conference, pp.1-4, 14-17 November 2006. 參考文獻

  48. [13] Ching-Hung Chang, P. Kourtessis and J. M. Senior, “GPON service level based dynamic bandwidth assignment protocol,” J. Electron. Lett., vol. 42, pp. 1173–1174, 2006. 參考文獻

  49. Q&A

  50. 附錄

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