1. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Chapter 4 TCP/IP Network Simulation

2. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Why Use Simulation

5. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Systematic Simulation Study

7. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Systematic Simulation Study  Pre-software stage  Define problem/objective  Design network model and select fixed parameters  Select performance metrics  Select variable parameters

8. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Systematic Simulation Study (Cont.)  Software stage  Model construction  Simulation configuration  Simulation execution/Data collection  Result presentation

9. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Types of Simulation

10. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Types of simulations  Continuos vs. discrete event  Terminating vs. steady state  Synthetic vs. trace-driven

11. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Trace-Driven Simulations  Actual network traces can be used as simulation input  Results can be more convincing

13. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Validation and Verification

14. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Confidence Level Analysis

16. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Confidence Level  Relative precision formula for 95% confidence (see Eq. 4.8, pp. 84)  Confidence level in terminating simulation GRepeat the entire simulation many times with different random numbers (or seeds) Gp105, Fig. 4.4

17. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Confidence Level (cont.)  Confidence level in steady-state simulation GFixed length simulation GAdaptive length simulation

18. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Self Similar Traffic

19. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Simulation Tools

21. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Classification of Simulation Tools  GPPL: General Purpose Programming Language  PSL: “Plain” Simulation Language  SP: Simulation Package  p110, Fig. 4.7

22. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Ns class hierarchy

24. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Reference network for TCP simulation with background traffic

25. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Sequence No. vs. time

26. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Average throughput vs buffer size

27. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Single FTP with trace-driven “star wars movie” internet traffic

28. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain TCP throughput vs time

29. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain TCP packet delay vs time

30. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain 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

31. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Modeling hierarchy in OPNET

32. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Screen shot of a network-level modeling in OPNET

33. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Screen shot of a node-level modeling in OPNET

34. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Screen shot of a process-level modeling in OPNET

35. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Editing pad of state executives for process modeling in OPNET

36. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Link editor dialog box to set parameters of a point to point link object

37. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Packet editor to specify or edit details of TCP header fields

38. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Packet Editor to specify or edit details of TCP header

39. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Probe Editor to collect seven different types of statistics

40. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Simulation Tool showing two different simulation sequences

41. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Main menu of Analysis Tool

42. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Network model for RED gateway

43. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Evolution of buffer occupancy under FIFO and RED

44. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Network model for fairness evolution

45. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Average TCP/UDP throughput under FIFO

46. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Average TCP/UDP throughput under RED

47. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Average TCP/UDP throughput under WFQ

48. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Selecting the Right Tool  Built-in libraries  Credibility  User-Friendliness  Technical support  Level of Details  Resource consumption  Cost

49. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain NS vs. OPNET  Both have emerged as de facto “standard” for simulating TCP/IP networks  P143, Table 4.6

50. Prentice HallHigh Performance TCP/IP Networking, Hassan-Jain Packet delay vs link capacity