「差別式」服務網路的架構具有可擴充性，用來
在目前的「盡力服務式」網路中提供網路服務品
質的保證。

在本篇論文中，我們將詳細介紹「差別式」服務
模型及「差別式」路由器的組合元件。我們也會
對相關的研究報告做一整理分類與討論，並指出
目前「差別式」服務網路所會共同遭遇的困難與
挑戰。然後，我們提出了一個「加權式公平分享」
的演算法，來解決這些困難與挑戰。

Differentiated services (Diffserv) is a scalable architecture and
is proposed to provide QoS guarantee services in the current
best effort network environment.

In this thesis, we will introduce the Diffserv model and the Diffserv
router components in detail. Related works proposed by researchers
to improve the performance of the Diffserv networks are categorized
and discussed. Common challenges in the Diffserv networks are
pointed out. Then a weighted fair share algorithm is proposed to solve
these challenges.

1．Introdcution ………………………………………………………………… 1
1.1．Integrated Services Networks ……………………………………… 2
1.2．Differentiated Services Networks ………………………………… 4
1.2.1．Assured Service ……………………………………………… 5
1.2.2．Premium Service …………………………………………… 6
1.3．DiffServ Architecture Model ……………………………………… 8
2．DiffServ Router Components ……………………………………………… 9
2.1．Configuration and Management Interface ………………………… 10
2.2．Traffic Conditioning Blocks (TCB) ……………………………… 11
2.2.1．Traffic Classification Element …………………………… 11
-Behavior Aggregate (BA) Classifier ……………………… 12
-Multi-Field (MF) Classifier ……………………………… 12
2.2.2．Traffic Conditioning Element ……………………………… 13
-Meter ……………………………………………………… 13
-Action Element …………………………………………… 14
Marker ………………………………………………… 14
Dropper ………………………………………………… 15
Shaper ………………………………………………… 15
Monitor ………………………………………………… 16
2.3．Routing Component ……………………………………………… 17
2.4．Queue Element …………………………………………………… 17
RED queue management ………………………………………… 18
RIO queue management ………………………………………… 19
2.5．RSVP Component ………………………………………………… 22
3．Related Work ……………………………………………………………… 23
3.1．Feedback Control Architecture …………………………………… 24
3.1.1．One-Bit Feedback Control ………………………………… 24
3.1.2．Feedback Control Extension ……………………………… 25
3.2．Modifying The TCP Protocol ……………………………………… 27
3.2.1．Limiting OUT Packet ……………………………………… 27
3.2.2．Two-Window TCP ………………………………………… 28
3.3．Modifying Components in DiffServ Routers ……………………… 29
3.3.1．Marker with Per-Flow State Information ………………… 29
3.3.2．Inverse-Rate Drop Policy ………………………………… 30
3.3.3．Adaptive Packet Marking ………………………………… 31
3.4．Other Issues ……………………………………………………… 32
4．Adding A New Component into DiffServ Routers ……………………… 33
4.1．TCP Rate Control ………………………………………………… 34
4.2．Common Challenges Faced in Today's DiffServ Networks
……………………………………………………………………… 36
Long RTTs versus short RTTs ……………………………………… 36
Large profiles versus small profiles ……………………………… 36
Battlenecked flows versus flows at slow start phase ……………… 37
4.3．A Weighted Fair Share Rate Allocation Algorithm ……………… 38
5．Simulation Results ……………………………………………………… 41
5.1．Simulation Topology ……………………………………………… 41
5.2．Simulation Parameters …………………………………………… 43
5-2．Simulation results ………………………………………………… 44
6．Conclusion and Future Work …………………………………………… 51
Reference …………………………………………………………………… 52
Appendix A: Some Terminology for DiffServ ……………………………… 55
Appendix B: Detail Simulation Results …………………………………… 58

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[2] Lixia Zhang, Stephen Deering, Deborah Estrin, Scott Shenker, Daniel Zappala, "RSVP: A New Resource Reservation Protocol," IEEE Network, September 1993.
[3] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. Weiss, "An architecture for differentiated services," RFC 2475, December 1998.
[4] 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.
[5] J. Heinanen, F. Baker, W. Weiss, J. Wroclawski, "Assured Forwarding PHB Group," RFC 2597, June 1999.
[6] V. Jacobson, K. Nichols, K. Poduri, "An Expedited Forwarding PHB," RFC 2598, June 1999.
[7] Sally Floyd, VanJacobson, "Random Early Detection Gateways for Congestion Avoidance," IEEE/ACM Transactions on Networking, August 1993.
[8] David D. Clark, Wenjia Fang, "Explicit allocation of best effort packet delivery service," November, 1997, http://diffserv.lcs.mit.edu/ exp-alloc-ddc-wf.pdf
[9] Y. Bernet, A. Smith, S. Blake, "Conceptual model of diffserv routers," Internet Draft, draft-ietf-diffserv-model-01.txt, October 1999.
[10] Wenjia Fang, Nabil Seddigh, Biswajit Nandy, "A Time Sliding Window Three Colour Marker," Internet Draft, draft-fang-diffserv-tc-tswtcm-00.txt, October 1999.
[11] J. Heinanen, Telia Finland, R. Guerin, "A Single Rate Three Color Marker," RFC2697, September 1999.
[12] J. Heinanen, Telia Finland, R. Guerin, "A Two Rate Three Color Marker," RFC2698, September 1999.
[13] ATM Forum Traffic Management 4.0
[14] Longsong Lin, Jeffrey Lo, Fang-Ching Ou, "A generic traffic conditioner," Internet Draft, draft-lin-diffserv-gtc-01.txt, August 1999.
[15] S. Kalyanaraman, D. Harrison, S. Arora, K. Wanglee, G. Guarriello, "A one-bit feedback enhanced differentiated services architecture," Internet Draft, March 1998.
[16] Hungkei Chow, Alberto Leon-Garcia, "A feedback control extension to differentiated services," Internet Draft, March 1999.
[17] Ikjun Yeom, A. L. Narasimha Reddy, "Realizing throughput guarantees in a differentiated services network," IEEE Conference 1999.
[18] Ikjun Yeom, A. L. Narasimha Reddy, "Impact of marking strategy on aggregated flows in a differentiated services network," Quality of Service, 1999. IWQoS '99. 1999 Seventh International Workshop on.
[19] Wu-chang Feng, Dilip D. Kandlur, Debanjan Saha, Kang G. Shin, "Adaptive packet marking for providing differentiated services in the Internet," Proceeding of Internet Conference On Network Protocols, October 1998.
[20] Nabil Seddigh, Biswajit Nandy, Peter Pieda, "Study of TCP and UDP Interaction for the AF PHB," Internet Draft, draft-nsbnpp-diffserv-udptcpaf-01.txt, September 1999.
[21] Mukul Goyal, Arian Durresi, Raj Jain, "Effect of number of drop precedences in assured forwarding," Internet Draft, June 1999.
[22] Nabil Seddigh, Biswajit Nandy, Peter Pieda, "Bandwidth assurance issues for TCP flows in a differentiated services network," to be submitted to Globecom99.
[23] R. Bless, K. Wehrle, "IP multicast in differentiated services networks," Internet Draft, draft-bless-diffserv-multicast-00.txt, September 1999.
[24] Shrikrishna Karandikar, Shivkumar Kalyanaraman, Prasad Bagal, Bob Packer, "TCP rate control,"http://www.ecse.rpi.edu/Homepages/ shivkuma/research/ papers/
[25] R. Satyavolu, K. Duvedi, S. Kalyanaraman, "Explicit rate control of TCP applications," 1999, http://www.ecse.rpi.edu/Homepages/ shivkuma/research/ papers/iwqos99-rate.ps
[26] Packeteer Inc., "Controlling TCP/IP bandwidth," white paper, http://www.packeteer.com/