NSF Program:	4095 SPECIAL PROJECTS IN NET RESEARCH
NSF Award Number:	ANI-9809332
Principal Investigators:	Weibo Gong  Dept. of Electrical and Computer Engineering University of Massachusetts, Amherst, MA 01003 James Kurose Dept. of Computer Science University of Massachusetts, Amherst, MA 01003 Donald F. Towsley Dept. of Computer Science University of Massachusetts, Amherst, MA 01003 David Nicol Dept. of Computer Science University of Dartmouth, Hanover, NH 03755
Graduate Students:	Daniel Ratton Figueiredo Dept. of Computer Science - University of Massachusetts Yang Guo Dept. of Electrical and Computer Engineering - University of Massachusetts Benyuan Liu Dept. of Computer Science - University of Massachusetts

Project Summary:

Researchers from the University of Massachusetts at Amherst and Dartmouth College jointly propose to perform fundamental research on developing a fluid simulation methodology that will enable efficient, multi-time-scale, hierarchical performance modeling of complex networks such as the next generation Internet. The proposed effort will allow networks to be more easily modeled and their performance to be evaluated significantly faster; it will make it possible to model significantly larger networks than before and to allow the tradeoffs between modeling accuracy and solution speed to be quantitatively assessed. The novel features of the proposed fluid modeling methodology include:

• Modeling at multiple time-scales. The proposed unified modeling framework provides for modeling system behavior at different time-scales, allowing for significant savings in simulation execution times when modeling at coarser time-scales. Development of formalmeans for quantitatively characterizing the potential loss of modeling accuracy when fast-time-scale behavior is modeled at a coarser time-scale is an important part of the framework.
• Hierarchical fluid modeling. The PIs demonstrate that multi-level (hierarchical) fluid modeling allows for abstraction of a potentially complex component of the simulation by a simpler model and substitution of this simpler model into the larger simulation. The PIs also develop rigorous techniques that can automatically identify when such substitution can be performed without significant loss of modeling accuracy...
• Efficiency in modeling complex systems. The PIs demonstrate that in addition to providing for multi-time-scale, multi-level modeling, fluid simulation can be significantly more efficient than traditional discrete event simulation. The PIs' initial work shows a 50-fold speedup in a uniprocessor fluid simulation speed over the discrete-event counterpart with little loss in modeling accuracy.
• Applicability in many problem domains. The PIs demonstrate that fluid simulation methodologies are ``plug and play'' in the sense that they can be applied equally well to the current Internet protocol suite, future real-time and multicast protocols, or ATM networks.

Fluid Simulation Readings:

• Jong Suk Ahn and Peter B. Danzig
  Packet network simulation: speedup and accuracy versus timing granularity
  IEEE/ACM Transactions on Networking, Volume 4, No. 5 (Oct. 1996) Pages 743-757.
• K. Kumaran and D. Mitra
  Performance and Fluid Simulations of a Novel Shared Buffer Management System
  Proc. IEEE INFOCOM 98, March 1998.
• Anlu Yan and Wei-Bo Gong
  Fluid Simulation for High Speed Networks
  Technical Report TR-96-CCS-1, Dept. of ECE, Univ. of Massachusetts.
  Proceedings of the 15th International Teletraffic Congress, Washington, D.C., June, 1997.
• G. Kesidis and A. Singh
  An Overview of Cell-Level ATM Network Simulation
  Proc. High Performance Computer Systems, Montreal, PQ, pp. 202-212, July 1995.
• G. Kesidis and J. Walrand
  Quick Simulation of ATM Buffers with On-off Markov Fluid Sources
  ACM TOMACS, V3, N3, pp. 269-276, Jul 1993.
• G. Kesidis, A. Singh, D. Cheung, W. Kwok
  Feasibility of Fluid-event-driven simulation for ATM Networks
  Proc. IEEE Globecom 1996
• B. Liu, Y. Guo, J. Kurose, D. Towsley, W. Gong
  Fluid Simulation of Large Scale Networks: Issues and Tradeoffs
  Proc. International Conference on Parallel and Distributed Processing Techniques and Applications (Las Vegas, NV, June 1999).
• Yang Guo, Weibo Gong, and Don Towsley
  Time-Stepped Hybrid Simulation (TSHS) for Large Scale Networks
  Proc. of INFOCOM 2000, Tel Aviv, Israel, March, 2000.
• Benyuan Liu, Daniel R. Figueiredo, Yang Guo, Jim Kurose, Don Towsley
  A Study of Networks Simulation Efficiency: Fluid Simulation vs. Packet-level Simulation
  To appear in Proceedings of IEEE Infocom 2001.

Fluid Simulation Framework:

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