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NS-2 網路模擬器介紹與使用

NS-2 網路模擬器介紹與使用. 吳賢明 國立中興大學　計算機及資訊網路中心 中華民國九十三年十月二十七日　. Agenda. 淺談網路模擬 NS2 簡介 NS2 架構 、 安裝與使用 視覺化實例演練 Q&A. Methods for network research. Analytical Model General expression or close form Emulation Network testbed Lab environment Real code Simulation Virtual network testbed.

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NS-2 網路模擬器介紹與使用

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  1. NS-2 網路模擬器介紹與使用 吳賢明 國立中興大學　計算機及資訊網路中心 中華民國九十三年十月二十七日　

  2. Agenda • 淺談網路模擬 • NS2簡介 • NS2架構、安裝與使用 • 視覺化實例演練 • Q&A

  3. Methods for network research • Analytical • Model • General expression or close form • Emulation • Network testbed • Lab environment • Real code • Simulation • Virtual network testbed

  4. Why Simulation • Study of implemented protocols and algorithms • Behavior • Performance • Test of unimplemented new protocols and algorithms • Comparison of results across research efforts

  5. 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

  6. 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

  7. Network simulators • Specific Purpose • ATM • Wireless • TCP/IP • General Purpose • Modifiable modules • Modules extensibility

  8. What features should a simulator provide ? • Easy network topology setup • Protocols and application implementation • TCP,UDP,… • FTP, Telnet, Web, CBR, VBR,… • Routing protocols • Queue management protocols • Configurability • Extensibility

  9. Agenda • 淺談網路模擬 • NS2簡介 • NS2架構、安裝與使用 • 視覺化實例演練 • Q&A

  10. 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 • NS2 is publicly available at http://www.isi.edu/nsnam/ns/ns-build.html

  11. About NS2 • 1989: REAL network simulator • 1995: DARPA VINT project at LBL, Xerox PARC, UCB, and USC/ISI • Present: DARPA SAMAN project and NSF CONSER project • Collaboration with other researchers including CIRI

  12. Ns Status • Periodical release (ns-2.27, Jan 2004) • ~200K LOC in C++ and Otcl, • ~120 test suites and 100+ examples • 392 pages of ns manual • Daily snapshot (with auto-validation) • Stability validation • http://www.isi.edu/nsnam/ns/ns-tests.html • Platform support • FreeBSD, Linux, Solaris, Windows and Mac • User base • > 1k institutes (50 countries), >10k users • About 300 posts to ns-users@isi.edu every month

  13. Ns functionalities • Wired • Transportation: 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

  14. “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

  15. Ns Models • Traffic models and applications: • Web, FTP, telnet, constant-bit rate, real audio • Transport protocols: • unicast: TCP (Reno, Vegas, etc.), UDP • Multicast: SRM • Routing and queueing: • Wired routing, ad hoc rtg and directed diffusion • queueing protocols: RED, drop-tail, etc • Physical media: • Wired (point-to-point, LANs), wireless (multiple propagation models), satellite

  16. Agenda • 淺談網路模擬 • NS2簡介 • NS2架構、安裝與使用 • 視覺化實例演練 • Q&A

  17. 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

  18. NS Architecture • Advantage • Reusability • Maintenance • Disadvantage • Performance (speed and memory) • Careful planning of modularity

  19. User’s view of NS2

  20. Architecture view of NS2

  21. Resources and Documentations • NS2 and related component • Tcl release 8.4.5 (required component) • Tk release 8.4.5 (required component) • Otcl release 1.8 (required component) • TclCL release 1.15 (required component) • Ns release 2.27 (required component) • Nam release 1.10 (optional component) • Xgraph version 12 (optional component) • CWeb version 3.4g (optional component) • SGB version 1.0 (?) (optional component, builds sgblib for all UNIX type platforms) • Gt-itm gt-itm and sgb2ns 1.1 (optional component) • Zlib version 1.1.4 (optional, but required should Nam be used)

  22. Resources and Documentation • Getting the pieces • Tcl/TK 8.x (Tcl-8.4.5 tk-8.4.5): http://www.isi.edu/nsnam/dist/tcltk • Otcl(1.8) and TclCL(1.15): http://sourceforge.net/project/showfiles.php?group_id=30174 • ns-2 and nam-1: http://www.isi.edu/nsnam/dist/ns-src-2.27.tar.gz • All-at-once http://www.isi.edu/nsnam/dist/ns-allinone-2.27.tar.gz

  23. Resources and Documents • Ns and nam build questions • http://www.isi.edu/nsnam/ns/ns-build.html • Ns mailing list: ns-users@isi.edu • Ns manual and tutorial (in distribution) • TCL: http://dev.scriptics.com/scripting • Otcl tutorial (in distribution): ftp://ftp.tns.lcs.mit.edu/pub/otcl/doc/tutorial.html

  24. Running ns-2 for Windows 9x/2000/XP under Cygwin • Cygwin • Cygwin is a Linux-like environment for Windows • ns-2 supports Cygwin • Get Cygwin from http://www.cygwin.com • ns-2 installation • From all pieces • All-at-once • http://www.isi.edu/nsnam/ns/ns-build.html

  25. Cygwin Installation

  26. ns-2 installation • Get the file : http://www.isi.edu/nsnam/dist/ns-allinone-2.27.tar.gz • Install files #tar zxvf ns-allinone-2.27.tar.gz #cd ns-allinone-2.27 #install • Configure system • Update user environment (~/.bashrc) export NS_HOME=/home/XXX/ns-allinone-2.27/ export PATH=$NS_HOME/tcl8.4.5/unix:$NS_HOME/tk8.4.5/unix:$NS_HOME/bin:$PATH export LD_LIBRARY_PATH=$NS_HOME/tcl8.4.5/unix:$NS_HOME/tk8.4.5/unix:\ $NS_HOME/otcl-1.8:$NS_HOME/lib:$LD_LIBRARY_PATH export TCL_LIBRARY=$NS_HOME/tcl8.4.5/library • For detail, ref to : http://www.sims.berkeley.edu/~christin/ns-cygwin.shtml

  27. ns-2 Directory Structure OTcl code

  28. Tcl Basic – Hello World #Define a process named "helloworld" proc helloworld {} { puts "Hello world!!!" } # Call the process helloworld Helloworld

  29. Tcl Basic – Another Example proc pow {x n} { if {$n == 1} { return $x } set part [pow $x [expr $n-1]] return [expr $x*$part] } set x 10 puts "x is $x" set y [pow $x 2] puts "y is $y" while { $x > 0 } { puts $x incr x -1 }

  30. # Create a class call "mom" and # add a member function call "greet" Class mom mom instproc greet {} { $self instvar age_ puts "$age_ years old mom say: How are you doing?" } # Create a child class of "mom" called "kid" # and overide the member function "greet" Class kid -superclass mom kid instproc greet {} { $self instvar age_ puts "$age_ years old kid say: What's up, dude?" } # Create a mom and a kid object set each age set a [new mom] $a set age_ 45 set b [new kid] $b set age_ 15 # Calling member function "greet" of each object $a greet $b greet OTcl - An Examplefrom:http://nile.wpi.edu/NS/

  31. Agenda • 淺談網路模擬 • NS2簡介 • NS2架構、安裝與使用 • 視覺化實例演練 • Q&A

  32. Using ns Problem Result analysis Simulation model Modify ns Setup/run simulation with ns

  33. TCP congestion control

  34. Retransmit Timeout TCP congestion control Connection Initialization Slow Start SSTHRESH Reached CongestionWindow Reduced to 1 Congestion Notified Fast Retransmission Timeout Again Congestion Avoidance ExponentialBackoff

  35. Simple Simulation Example IDisplay Result with nam Animation FTP n2 tcp 2 mbps, 10 ms 1.7 mbps, 20 ms n0 n1 sink FTP sec 4.0 0.5 3.0

  36. #Create a simulator object set ns [new Simulator] #Define different colors for data flows (for NAM) $ns color 1 Blue #Open the NAM trace file set nf [open out.nam w] $ns namtrace-all $nf #Define a 'finish' procedure proc finish {} { global ns nf $ns flush-trace #Close the NAM trace file close $nf #Execute NAM on the trace file exec nam out.nam & exit 0 } #Create three nodes set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] #Create links between the nodes $ns duplex-link $n0 $n1 1.7Mb 20ms DropTail $ns duplex-link $n2 $n0 2Mb 10ms DropTail #Set Queue Size of link (n0-n1) to 5 $ns queue-limit $n0 $n1 5 #Give node position (for NAM) $ns duplex-link-op $n0 $n1 orient right $ns duplex-link-op $n2 $n0 orient right #Monitor the queue for link (n0-n1). (for NAM) $ns duplex-link-op $n0 $n1 queuePos 0.5 #Setup a TCP connection set tcp [new Agent/TCP] $tcp set class_ 2 $ns attach-agent $n2 $tcp set sink [new Agent/TCPSink] $ns attach-agent $n1 $sink $ns connect $tcp $sink $tcp set fid_ 1 #Setup a FTP over TCP connection set ftp [new Application/FTP] $ftp attach-agent $tcp $ftp set type_ FTP #Schedule events for the FTP agents $ns at 0.5 "$ftp start" $ns at 3.0 "$ftp stop" #Call the finish procedure after 4 seconds of #simulation time $ns at 4.0 "finish" #Run the simulation $ns run Source of Example I

  37. FTP1 n2 tcp1 sink1 n0 n1 sink2 n3 tcp2 FTP2 FTP2 FTP1 sec 4.0 0.5 3.0 3.5 Simple Simulation Example IIDisplay Result with nam Animation 2 mbps, 10 ms 2 mbps, 20 ms 2 mbps, 10 ms

  38. ….. #Create four nodes …. #Create links between the nodes …. #Set Queue Size of link (n0-n1) to 5 …. #Give node position (for NAM) …. #Monitor the queue for link (n0-n1). (for NAM) …. #Setup a TCP connection set tcp1 [new Agent/TCP] set tcp2 [new Agent/TCP] $tcp1 set class_ 2 $tcp2 set class_ 2 $ns attach-agent $n2 $tcp1 $ns attach-agent $n3 $tcp2 set sink1 [new Agent/TCPSink] set sink2 [new Agent/TCPSink] $ns attach-agent $n1 $sink1 $ns attach-agent $n1 $sink2 $ns connect $tcp1 $sink1 $ns connect $tcp2 $sink2 $tcp1 set fid_ 1 $tcp2 set fid_ 2 #Setup two FTP over TCP connection set ftp1 [new Application/FTP] set ftp2 [new Application/FTP] $ftp1 attach-agent $tcp1 $ftp2 attach-agent $tcp2 $ftp1 set type_ FTP $ftp2 set type_ FTP #Schedule events for the FTP agents $ns at 0 "$ftp2 start" $ns at 0.5 "$ftp1 start" $ns at 3.0 "$ftp1 stop" $ns at 3.5 "$ftp2 stop" #Call the finish procedure after 4 seconds of #simulation time $ns at 4.0 "finish" #Run the simulation $ns run Source of Example II

  39. FTP n2 tcp sink1 n0 n1 null n3 udp cbr cbr ftp sec 4.0 0.5 3.0 3.5 Simple Simulation Example IIIDisplay Result with nam Animation 2 mbps, 10 ms 2 mbps, 20 ms 2 mbps, 10 ms Size : 1 kByte Rate: 1 mbps

  40. …. #Setup a TCP connection set tcp [new Agent/TCP] $tcp set class_ 2 $ns attach-agent $n2 $tcp set sink [new Agent/TCPSink] $ns attach-agent $n1 $sink $ns connect $tcp $sink $tcp set fid_ 1 #Setup a FTP over TCP connection set ftp [new Application/FTP] $ftp attach-agent $tcp $ftp set type_ FTP #Setup a UDP connection set udp [new Agent/UDP] $ns attach-agent $n3 $udp set null [new Agent/Null] $ns attach-agent $n1 $null $ns connect $udp $null $udp set fid_ 2 #Setup a CBR over UDP connection set cbr [new Application/Traffic/CBR] $cbr attach-agent $udp $cbr set type_ CBR $cbr set packet_size_ 1000 $cbr set rate_ 1mb $cbr set random_ false #Schedule events for the CBR and FTP agents $ns at 0 "$cbr start" $ns at 0.5 "$ftp start" $ns at 3.0 "$ftp stop" $ns at 3.5 "$cbr stop" #Call the finish procedure after 4 seconds of #simulation time $ns at 4.0 "finish" #Print CBR packet size and interval puts "CBR packet size = [$cbr set packet_size_]" puts "CBR interval = [$cbr set interval_]" #Run the simulation $ns run Source of Example III

  41. Trace Analysis • Open NAM trace file set nam_file_var [open out_nam_file w] $ns namtrace-all $file_var • Open raw data trace file set data_file_var [open out_data_file w] $ns trace-all $data_file_var

  42. NAM trace file example …. V -t * -v 1.0a5 -a 0 A -t * -n 1 -p 0 -o 0xffffffff -c 31 -a 1 A -t * -h 1 -m 2147483647 -s 0 c -t * -i 1 -n Blue n -t * -a 0 -s 0 -S UP -v circle -c black -i black n -t * -a 1 -s 1 -S UP -v circle -c black -i black n -t * -a 2 -s 2 -S UP -v circle -c black -i black l -t * -s 0 -d 1 -S UP -r 1700000 -D 0.02 -c black -o right l -t * -s 2 -d 0 -S UP -r 2000000 -D 0.01 -c black -o right q -t * -s 1 -d 0 -a 0.5 q -t * -s 0 -d 1 -a 0.5 + -t 0.5 -s 2 -d 0 -p tcp -e 40 -c 1 -i 0 -a 1 -x {2.0 1.0 0 ------- null} - -t 0.5 -s 2 -d 0 -p tcp -e 40 -c 1 -i 0 -a 1 -x {2.0 1.0 0 ------- null} h -t 0.5 -s 2 -d 0 -p tcp -e 40 -c 1 -i 0 -a 1 -x {2.0 1.0 -1 ------- null} r -t 0.51016 -s 2 -d 0 -p tcp -e 40 -c 1 -i 0 -a 1 -x {2.0 1.0 0 ------- null} + -t 0.51016 -s 0 -d 1 -p tcp -e 40 -c 1 -i 0 -a 1 -x {2.0 1.0 0 ------- null} - -t 0.51016 -s 0 -d 1 -p tcp -e 40 -c 1 -i 0 -a 1 -x {2.0 1.0 0 ------- null} h -t 0.51016 -s 0 -d 1 -p tcp -e 40 -c 1 -i 0 -a 1 -x {2.0 1.0 -1 ------- null} …. Read and interpreted by NAM for animation display

  43. r : receive (at to node) • +: enqueue (at queue) • : dequeue (at queue) • d : drop (at queue) node.port Raw data trace file format and example (from example III) 1 2 6 8 10 11 3 4 5 7 9 12 …. + 0.884 1 2 cbr 1000 ------- 2 1.0 3.1 98 98 - 0.884 1 2 cbr 1000 ------- 2 1.0 3.1 98 98 r 0.89 1 2 cbr 1000 ------- 2 1.0 3.1 97 97 + 0.89 2 3 cbr 1000 ------- 2 1.0 3.1 97 97 - 0.89 2 3 cbr 1000 ------- 2 1.0 3.1 97 97 r 0.890706 2 3 cbr 1000 ------- 2 1.0 3.1 94 94 + 0.892 1 2 cbr 1000 ------- 2 1.0 3.1 99 99 - 0.892 1 2 cbr 1000 ------- 2 1.0 3.1 99 99 r 0.898 1 2 cbr 1000 ------- 2 1.0 3.1 98 98 + 0.898 2 3 cbr 1000 ------- 2 1.0 3.1 98 98 - 0.898 2 3 cbr 1000 ------- 2 1.0 3.1 98 98 r 0.898706 2 3 cbr 1000 ------- 2 1.0 3.1 95 95 ….

  44. Jitter Monitor

  45. RED Queue Monitor ExampleAn example by Polly Huang from http://nile.wpi.edu.tw/NS/Example/red/tcl ftp1 sink1 s3 s1 tcp1 10 mbps, 2 ms sink2 max_win=15 10 mbps, 4 ms r1 1.5 mbps, 20 ms r2 RED(size=25) max_win=15 10 mbps, 3 ms s2 tcp2 ftp2 ftp1 ftp2 sec 10 3.0 0

  46. .... set tcp1 [$ns create-connection TCP/Reno $node_(s1) TCPSink $node_(s3) 0] $tcp1 set window_ 15 set tcp2 [$ns create-connection TCP/Reno $node_(s2) TCPSink $node_(s3) 1] $tcp2 set window_ 15 set ftp1 [$tcp1 attach-source FTP] set ftp2 [$tcp2 attach-source FTP] # Tracing a queue set redq [[$ns link $node_(r1) $node_(r2)] queue] set tchan_ [open all.q w] $redq trace curq_ $redq trace ave_ $redq attach $tchan_ .... proc finish {} { global tchan_ set awkCode { { if ($1 == "Q" && NF>2) { print $2, $3 >> "temp.q"; set end $2 } else if ($1 == "a" && NF>2) print $2, $3 >> "temp.a"; } } set f [open temp.queue w] puts $f "TitleText: red" puts $f "Device: Postscript" if { [info exists tchan_] } { close $tchan_ } exec rm -f temp.q temp.a exec touch temp.a temp.q exec awk $awkCode all.q puts $f \"queue exec cat temp.q >@ $f puts $f \n\"ave_queue exec cat temp.a >@ $f close $f exec xgraph -bb -tk -x time -y queue temp.queue & exit 0 } $ns run

  47. RED Queue Monitor Example

  48. More … • OTcl linkage (with C++ classes) • Variable export • Control command export • Recompilation • Extend NS-2 • Modify existed object • Add new application • Add new agent • … • NS-2 main page • http://wwww.isi.edu/nsnam/ns

  49. Q & A

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