1 / 25

Chapter 4

Chapter 4. TCP/IP Network Simulation. Objectives. Appreciate the role of simulation in performance evaluation of TCP/IP networks Acquire the knowledge needed to conduct steady state simulation Master basic skills for analyzing confidence level Describe types of simulation tools available

alcina
Download Presentation

Chapter 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 4 TCP/IP Network Simulation

  2. Objectives • Appreciate the role of simulation in performance evaluation of TCP/IP networks • Acquire the knowledge needed to conduct steady state simulation • Master basic skills for analyzing confidence level • Describe types of simulation tools available • Familiarize with the capabilities of popular simulation tools

  3. Contents • Why use simulation • Systematic simulation study • Types of simulations • Simulation validation and verification • Confidence level of simulation results • Simulation with self similar traffic • Simulation tools

  4. Why Use Simulation

  5. Why Use Simulation • Predict performance for proposed network • Allow performance evaluation under a wide variety of network conditions • Compare alternative architectures under identical and repeatable conditions • Produce results closer to reality • Validate analytical results

  6. Systematic Simulation Study

  7. Systematic Simulation Study • Pre-software stage • Define problem/objective • Design network model and select fixed parameters • Select performance metrics • Select variable parameters

  8. Systematic Simulation Study (Cont.) • Software stage • Model construction • Simulation configuration • Simulation execution/Data collection • Result presentation

  9. Types of Simulation

  10. Types of simulations • Continuos vs. discrete event • Terminating vs. steady state • Synthetic vs. trace-driven

  11. Steady State • If we are interested in asymptotic behavior of a network system, we cannot use terminating simulations • Must continue until it reaches steady state

  12. Trace-Driven Simulations • Actual network traces can be used as simulation input • Results can be more convincing

  13. Validation and Verification

  14. Simulation Validation and Verification • Validation: Make sure that the assumptions are realistic • Verification: Make sure that the model implements assumptions correctly • Guidelines to follow • Look for “surprise” in output • Employ analytical modeling • Compare with real network data

  15. Confidence Level Analysis

  16. Confidence Level • Relative precision formula for 95% confidence (see Eq. 4.8, pp. 84) • Confidence level in terminating simulation • Repeat the entire simulation many times with different random numbers (or seeds) • p105, Fig. 4.4

  17. Confidence Level (cont.) • Confidence level in steady-state simulation • Fixed length simulation • Adaptive length simulation

  18. Self Similar Traffic

  19. Self Similar Traffic • Poisson model does not capture the burstiness of TCP/IP traffic • TCP/IP traffic usually exhibits self similar property • Generated by superimposing many ON/OFF sources with Pareto distribution

  20. Simulation Tools

  21. Classification of Simulation Tools • GPPL: General Purpose Programming Language • PSL: “Plain” Simulation Language • SP: Simulation Package • p110, Fig. 4.7

  22. NS Simulator • Developed by UC Berkeley • Public domain SP • Object-oriented • Written in C++ and object-oriented tcl (Otcl) • Network components are represented by classes

  23. OPNET • Developed by OPNET Technologies Inc. • Commercial SP • Object-oriented • Totally menu-driven package • Built-in model libraries contain most popular protocols and applications • Simulation task made easy

  24. Selecting the Right Tool • Built-in libraries • Credibility • User-Friendliness • Technical support • Level of Details • Resource consumption • Cost

  25. NS vs. OPNET • Both have emerged as de facto “standard” for simulating TCP/IP networks • P143, Table 4.6

More Related