目前在差別性服務網路上(Differentiated Service, Diffserv )保證資料流端點對端點(End-to-End)的服務品質(Quality of Services, QoS)仍有欠缺在。因此我們提出一個有效的傳輸率恢復機制(Throughput-Recovery Mechanism)，使得最高優先權的資料流可以獲得適當的資源分配達到應有的服務品質，藉以改進目前在差別性服務網路上無法針對個別資料流在服務品質上的保證。
我們所提出的傳輸率恢復機制，主要是針對低延遲的EF PHB的個別資料流提供事先定義的Minimum Departure Rate的保證，我們的機制主要分為兩部分，一部份為回朔式(Feedback)自我調整機制，藉由出口節點(Egress Node)對資料流傳輸率的量測，以進行回朔式自我調整機制決定是否啟動，透過以TCP/IP為基礎的回朔式自我調整機制訊息(Feedback Self-Adaptive Control Message)通知入口節點(Ingress Node)，由入口節點進行適當的網路資源分配，使最高優先權的資料流可以獲得傳輸率的改善。另一部份，我們在差別性服務網域(Diffserv Domain)中的核心路由器(Core Router)中加入了動態權值調整(Dynamic Weight Adjustment)之WRR機制，使得資料流不會因為核心路由器的因素而達不到應有的品質保證。
透過我們建立的Markov Chain數學模型以及在NS-2網路模擬程式中加入我們的傳輸率恢復機制，其結果可以驗證我們的傳輸率恢復機制是可以使EF資料流獲得應有傳輸率的提昇。最後我們改進我們的權值調整機制，其結果證明是可以進一步改善EF資料流的延遲及傳輸率。

It is known that to pursuit end-to-end QoS of a class-based traffic flow is inefficient in Differentiated Service Networks. Therefore in this thesis, we propose an effective throughput-recovery mechanism to allow high-priority traffic flow to receive suitable resource
allocation, and hence the end-to-end QoS is guaranteed.
The proposed throughput-recovery mechanism assures a predefined minimum departure rate of low-latency EF dataflow. It consists of two parts. The first part is referred to as the feedback self-adaptive mechanism, where the egress node measures and monitors throughput of EF dataflow to decide whether to send the control messages to ingress node. When ingress node receives the control messages, it will reallocate the resources to improve EF throughput. The second part is referred to as the dynamic weight adjustment mechanism, which can prevent EF packets from
dropping when congestion occurs in the core routers.
For the purpose of demonstration, we build a mathematical model and use NS-2 simulator. We have proved our throughput-recovery mechanism is effective in improving the throughput of EF traffic flow. Finally, we modify the traditional WRR such that it can adjust weight based on the
delay requirements.

目 錄

第一章 導論 ..............................................................1
1.1 研究動機 .............................................................1
1.2 研究方法與方向 .......................................................1
1.3 章節架構 .............................................................2

第二章 網際網路上之服務品質保證 ..........................................4
2.1 整合性服務(Integrated Service,Intserv) ...............................5
2.2 差別性服務(Differentiated Service, Diffserv) .........................6
2.2.1 差別性服務欄位(Diffserv Field)簡介Service,Intserv) .................6

2.2.2 差別性服務網路架構 .................................................8
2.3 相關研究 .............................................................12
2.3.1 回朔式控制差別性服務網路(Feedback Controlled Diffserv)架構 .........12
2.3.2 動態調整封包標記引擎(Packet-Marking Engine)架構 ....................13
2.3.3 動態分散式(Dynamic-Distributed)的差別性服務網路架構 ................14
2.3.4 聚集資料流控制(Aggregate Flow Control, AFC)架構 ....................16
2.3.5 具有測量根據的連線導向式保證服務(MCOAS)架構 ........................17
2.3.6 動態WFQ(Dynamic Weighted Fair Queue)架構 ...........................19
2.3.7 Simple Model of TCP Behavior in A Diffserv Network .................20
2.4 本論文的改進方法 .....................................................21

第三章 傳輸率恢復機制的差別性服務網路架構 ................................24
3.1 具有傳輸率恢復機制的差別性服務網路 ...................................24
3.2 回朔式(Feedback)自我調整機制 .........................................26
3.2.1 回朔式自我調整機制之控制訊息 .......................................27
3.2.2 節點的設計 .........................................................28
3.3 動態調整權值(Dynamic Weight Adjustment)之WRR機制 .....................33
3.3.1 動態調整權值(Dynamic Weight Adjustment)機制 ........................33
3.3.2 具動態調整權值機制之節點設計 .......................................34

第四章 數學模型與設計 ....................................................36
4.1 數學模型架構與參數 ...................................................36
4.2 Markov Chain運算過程 .................................................42

第五章 數學與模擬結果 ....................................................46
5.1 NS-2模擬架構介紹 ............................................46
5.2 支援自我恢復機制之NS-2 ...............................................47
5.3 數學與模擬結果 .......................................................51
5.3.1 數學模型架構之模擬拓樸 .............................................52
5.3.2 改進式的WRR Model(Improved WRR) ....................................62
5.3.3 使用TCP協定的傳輸率回覆機制模擬結果 ................................65

第六章 結論與未來工作方向 ................................................68
6.1 結論 .................................................................68
6.2 未來工作方向 .........................................................69

參考文獻 ..................................................................71
索引 ......................................................................75

參考文獻（References）

[1] Jon Postel Editor, "INTERNET PROTOCOL", RFC 791, September 1981.
[2] S. Deering, R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification",
RFC2460, December 1998.
[3] R. Braden, D. Clark, S. Shenker, "Integrated Services in the Internet
Architecture: an Overview", RFC1633, June 1994.
[4] R. Braden, Ed., L. Zhang, S. Berson, S. Herzog, S. Jamin, "Resource
ReSerVation Protocol (RSVP)", RFC 2205, September 1997.
[5] J. Wroclawski, "Specification of the Controlled-Load NetworkElement
Service", RFC 2211, September 1997.
[6] S. Shenker, C. Partridge, R. Guerin, "Specification of Guaranteed Quality
of Service", RFC 2212, September 1997.
[7] K. Nichols, S. Blake, F. Baker, D. Black, "Definition of the Differentiated
Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December
1998.
[8] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. Weiss, "An
Architecture for Differentiated Services", RFC 2475, December 1998.
[9] Y. Bernet , S. Blake , D. Grossman , A. Smith , "An Informal Management
Model for Diffserv Routers", Internet-Draft(draft-ietf-diffserv-model-
06.txt), February 2001.
[10] J. Heinanen, F. Baker, W. Weiss, J. Wroclawski, "Assured Forwarding PHB
Group", RFC 2597, June 1999.
[11] V. Jacobson, K. Nichols, K. Poduri, "An Expedited Forwarding PHB", RFC
2598,June 1999.
[12] Hungkei (Keith) Chow, "A Feedback Control Extension to Differentiated
Services", Internet-Draft(draft-chow-diffserv-fbctrl-00.txt), March 1999.
[13] Wu-Chang Feng, Dilip D. Kandlur, Debanjan Saha, and Kang G.
Shin, "Adaptive Packet Marking for Maintaining End-to-End Throughput in a
Differentiated-Services Internet", IEEE/ACM Transactions on Networking,
Vol. 7, NO. 5, October 1999.
[14] Hai,D.Q., Vuong, S.T., "Dynamic-distributed differentiated service for
multimedia applications", Proceedings International Conference on
Dependable Systems and Networks, 2000, Page(s): 586 -594.
[15] Nandy, B., Ethridge, J., Lakas, A., Chapman, A., "Aggregate flow control:
improving assurances for differentiated services network", IEEE INFOCOM
2001. Proceedings. Volume: 3, 2001, Page(s): 1340 -1349.
[16] Xiaoning He, Hao Che, "Achieving end-to-end throughput guarantee for TCP
flows in a differentiated services network ", Ninth International
Conference on Computer Communications and Networks, 2000, Page(s): 69 -74.
[17] Chin-Chang Li, Shio-Li Tsao, Meng Cheng Chen, Yeali Sun, Yuch-Min
Huang, "Proportional delay differentiation service based on weighted fair
queuing", Ninth International Conference on Computer Communications and
Networks, 2000, Page(s): 418 -423.
[18] Yeom I., Reddy A.L.N.,"Modeling TCP behavior in a differentiated services
network", IEEE/ACM Transactions on Networking, Volume: 9 Issue: 1 , Feb. ,
2001 Page(s): 31 –46.
[19] Floyd S., Jacobson V., "Random early detection gateways for congestion
avoidance", IEEE/ACM Transactions on Networking, Volume: 1 Issue: 4 , Aug.
1993 Page(s): 397 -413.
[20] Clark D.D., Wenjia Fang, "Explicit allocation of best-effort packet
delivery service", IEEE/ACM Transactions on Networking, Volume: 6 Issue:
4, Aug. 1998 Page(s): 362 -373.
[21] Byung G. Kim, Bo-Kyoung Kim, "Simulation Study of Weighted Round-Robin
Queueing Policy", Proceedings of Technical Conference on
Telecommunications R&D in Massachusetts, October 1994.
[22] Floyd S., Jacobson V., "Link-sharing and resource management models for
packet networks", IEEE/ACM Transactions on Networking, Volume: 3 Issue: 4,
Aug. 1995, Page(s): 365 -386.
[23] Sally Floyd, "Issuses in Flexible Resource Management for Datagram
Networks", 3rd Workshop on Very High Speed Networks, March 9, 1992.
[24] Alan Demers, Scott Shenker, "Analysis and Simulation of a Fair Queueing
Algorithm", Symposium proceedings on Communications architectures &
protocols, September 1989.
[25] W.C. Feng, D.D. Kandlur, D. Saha, K.G. Shin, "Understanding and Improving
TCP Performance Over Networks with Minimum Rate Guarantees", IEEE/ACM
Transactions on Networking, Vol. 7, NO.2, April 1999, pp. 173-187.
[26] Sally Floyd, Van Jacobson, "On Traffic Phase Effects in Packet-Switched
Gateways", Lawrence Berkeley Laboratory, 1992.
[27] Network Research Group, Lawrence Berkeley National Laboratory(LBNL), "NS
version 1 – LBNL Network Simulator", http://www-nrg.ee.lbl.gov/ns/
[28] UC Berkeley, "UCB/LBNL/VINT Network Simulator – ns(version2)", http://www-
mash.cs.berkeley.edu/ns/

[29] John Ousterhout, "History of Tcl ",
http://dev.ajubasolutions.com/doc/tclHistory.html
[30] David Wetherall, MIT Lab for Computer Science, "OTcl – MIT Object Tcl The
FAQ & Manual", ver0.96, Sep. 1995.
[31] UC Berkeley, " UCB/LBNL Network Simulator：Contributed Code ", http://www-
mash.cs.berkeley.edu/ns/ns-contributed.html
[32] Sea Murphy, "Diffserv additions to ns-2",
http://www.teltec.dcu.ie/~murphy/ns-work/diffserv/index.html , May 2000.
[33] M. Shreedhar and G. Varghese, "Efficient Fair Queueing using Deficit Round
Robin", Proc. ACM SIGCOMM 95, 1995.