柯志亨老师的ns2课件

柯志亨老师的ns2课件

Network Simulation and Analysis---Using NS2

Chih-Heng Ke (柯志亨)Webpage: http://hpds.ee.ncku.edu.tw/~smallko Email: smallko@ee.ncku.edu.tw MSN: smallko@http://doc.guandang.net

柯志亨老师的ns2课件

Methods for network research Analytical– Model – General expression or close form

Emulation– Network testbed – Lab environment – Real code

Simulation– Virtual network testbed

柯志亨老师的ns2课件

Why Simulation Study of implemented protocols and algorithms– Behavior – Performance

Test of unimplemented new protocols and algorithms

Comparison of results across research efforts

柯志亨老师的ns2课件

Simulation -- Advantage Inexpensive, Flexible and Reconfigurable Network phenomena interested can be reproduced Opportunity to study large-scale network

Easier comparison of results across research efforts

柯志亨老师的ns2课件

Simulation -- Disadvantage Important network details may be missed Protocols or algorithms must be “added” before simulation can be done High start-up cost Have to be carefully verified before the test results can be used

柯志亨老师的ns2课件

Outline1 NS2 Introduction and Installation– – – – – cygwin installation ns2.26, ns2.27, ns2.28, ns2.29, myNS2, others How to apply the patch New module insertion Recompilation

Tools– nsbench – NS2 Scenarios Generator (NSG)

柯志亨老师的ns2课件

Outline2 How to measure the loss rate, delay, jitter, throughput?– parse the trace file – use ―LossMonitor‖ agent – modify the C++ code

How to present the simulation result?– gnuplot (xgraph, or Excel) – random number generator – confidence interval How to run the simulation in a batch mode?

柯志亨老师的ns2课件

Outline3 How CBR works? How UDP works? How DCF works ?– Trace the C++ code in NS2 Multicast Unicast

Propagation Model– Transmission range

柯志亨老师的ns2课件

Outline4 wireless error model– random uniform model – GE model (burst pattern) – Others

DCF vs. EDCF– Adaptive Approach for QoS Support in IEEE 802.11e Wireless LAN

柯志亨老师的ns2课件

Outline5 How to dynamically set the link bandwidth during simulation? How to set the different operation modes (DCF or EDCF) for different mobile nodes? How to set the different transmission speeds to different mobile nodes? How to measure the queue length in the base station or mobile node? How to set the communication radius in wireless nodes? Hidden Terminal Problem How to get the information in different layers?

柯志亨老师的ns2课件

Outline6 Multimedia simulation– myEvalvid (encoding from raw YUV video) – myEvalvid-NT (for publicly available video traffic traces) – Multiple Description Coding (MDC) – voip simulation

柯志亨老师的ns2课件

What is NS-2 NEST (Network Simulation Testbed) REAL (Realistic and Large) NS-1 NS-2 NS-2 is a common network simulator NS-2 is developed by the VINT project in order to reduce duplication of effort within the network research and develop community http://www.isi.edu/nsnam

柯志亨老师的ns2课件

Ns functionalities Wired– – – – – Transportatio

n: TCP,UDP,RTP,SRM Traffic sources:web, ftp, telnet, cbr, stochastic Queuing disciplines:drop-tail, RED, FQ, SFQ, DRR QoS: IntServ and Diffserv Emulation

Wireless– Ad hoc routing and mobile IP – Directed diffusion, sensor-MAC

Tracing, visualization, various utilities

柯志亨老师的ns2课件

“Ns” Components Ns, the simulator itself Nam, the network animator– Visualize ns (or other) output – Nam editor: GUI interface to generate ns scripts

Pre-processing:– Traffic and topology generators

Post-processing:– Simple trace analysis, often in awk, perl, or Tcl

柯志亨老师的ns2课件

NS Architecture Split-Programming Model– C++ implement the simulation model Implement data path per packet processing, core of ns fast to run, detailed, complete control

– OTcl (Tcl script language with Object-oriented extensions developed at MIT ) Simulation scenario configurations Periodic or triggered action Manipulating existing C++ objects fast to write and change

柯志亨老师的ns2课件

The simulation procedureProblems Simulate the environment Run with ns-2 Analysis the result Yes Finish simulation

Modify the simulation

No