Part 3. Result Analysis

Transcription

1 Introduction to NS-2 Part 3. Result Analysis Min Chen School of Computer Science and Engineering Seoul National University 1

2 Outline A Simulation and its results The Format of Trace File The AWK language Result Analysis End-to-End Delay Jitter Packet Loss Figure Output GNUplot 2

3 A Simulation: TCP and UDP TCP and UDP Queuing 1 s ~ 4.0 s ftp tcp s1 sink r d s2 null 0.1 s ~ 4.5 s cbr udp 3

4 The OTcl Script set s1 [$ns node] set s2 [$ns node] set r [$ns node] set d [$ns node] $ns duplex link $s1 $r 2Mb 10ms DropTail $ns duplex link $s2 $r 2Mb 10ms DropTail $ns duplex link $r $d 1.7Mb 20ms DropTail $ns queue limit $r $d 10 $ns duplex link op $s1 $r orient right down $ns duplex link op $s2 $r orient right up $ns duplex link op $r $d orient right $ns duplex link op $r $d queuepos 0.5 4

5 The OTcl Script set tcp [new Agent/TCP] $ns attach agent $s1 $tcp set sink [new Agent/TCPSink] $ns attach agent $d $sink $ns connect $tcp $sink $tcp set fid_ 1 set ftp [new Application/FTP] $ftp attach agent $tcp $ftp set type_ FTP 5

6 The OTcl Script set udp [new Agent/UDP] $ns attach agent $s2 $udp set null [new Agent/Null] $ns attach agent $d $null $ns connect $udp $null $udp set fid_ 2 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 6

7 The OTcl Script $ns at 0.1 "$cbr start" $ns at 1.0 "$ftp start" $ns at 4.0 "$ftp stop" $ns at 4.5 "$cbr stop" $ns at 4.5 "$ns detach agent $s1 $tcp; $ns detach agent $d $sink" $ns at 5.0 "finish" 7

8 NAM Result 8

9 Trace File cbr cbr cbr cbr r cbr cbr cbr cbr cbr r cbr cbr cbr cbr cbr r cbr cbr cbr cbr

10 Trace Format cbr Event Time From node To node Packet Type Packet Size Flags Flow ID Source address Destination address Sequence number Packet ID r: receive +: enqueue : dequeue d: drop src_node.port dest_node.port 10

11 AWK Language Designed for text analysis Similar to C but more simple Read the records line by line $0: the whole string in the corresponding line $1: the first data in the corresponding line $2: the second data in the corresponding line cbr $1 $2 $3 $4 $5 $6 $7 $8 $9 $10 $11 $12 11

12 AWK Language (Cont.) Three parts in the AWK code BEGIN Process END Process Procedure 1) Read one record 2) Update the parameters 3) Run the Pattern Code 4) Repeat until no record remain 12

13 An AWK Example AWK Code: awk.awk file BEGIN{ sum=0; } { } if($1=="+") { sum++; } END{ printf("the number of enqueue is: %d\n",sum); } 13

14 An AWK Example (Cont.) Use the awk.awk to anlyze the out.tr trace file ~$ awk -f awk.awk out.tr Output the results into sum.txt ~$ awk -f awk.awk out.tr > sum.txt 14

15 Analysis 1: End-to-End Delay Calculate the duration of a packet End to End Delay = End Time Start Time r d End Time s2 Start Time In this example, we calculate the end-to-end delay for the cbr traffic via udp transmission 15

16 Analysis 1: End-to-End Delay(Cont.) BEGIN { highest_packet_id=0; } { action = $1; time = $2; from = $3; to = $4; type = $5; pktsize = $6; flow_id = $8; src = $9; dst = $10; seq_no = $11; packet_id = $12; if ( packet_id > highest_packet_id ) highest_packet_id = packet_id; if ( start_time[packet_id] == 0 ) start_time[packet_id] = time; if ( flow_id == 2 && action!= "d" ) { if( action == "r" ) { end_time[packet_id] = time; } else { end_time[packet_id] = -1; } } } 16

17 Analysis 1: End-to-End Delay(Cont.) END { for(packet_id=0; packet_id < highest_packet_id; packet_id++) { start = start_time[packet_id]; end = end_time[packet_id]; packet_duration = end-start; if( start < end ) { printf("%f %f\n",start, packet_duration); } } } 17

18 Analysis 1: End-to-End Delay(Cont.) ~$ awk -f delay.awk out.tr > delay.txt delay.txt:

19 Analysis 2: Jitter Jitter represents the variance of delay Jitter = ( (EndTime(j)-StartTime(j)) - (EndTime(i)-StartTime(i)) ) / (j i) In this example, we calculate the jitter for the cbr traffic via udp transmission 19

20 Analysis 2: Jitter(Cont.) BEGIN { highest_packet_id=0; } { action = $1; time = $2; from = $3; to = $4; type = $5; pktsize = $6; flow_id = $8; src = $9; dst = $10; seq_no = $11; packet_id = $12; if ( packet_id > highest_packet_id ) highest_packet_id = packet_id; if ( start_time[packet_id] == 0 ) { pkt_seqno[packet_id] = seq_no; start_time[packet_id] = time; } if ( flow_id == 2 && action!= "d" ) { if( action == "r" ) { end_time[packet_id] = time; } else { end_time[packet_id] = -1; } } } 20

21 Analysis 2: Jitter(Cont.) END { last_sequno = 0; last_delay = 0; seqno_diff = 0; for(packet_id=0; packet_id < highest_packet_id; packet_id++) { start = start_time[packet_id]; end = end_time[packet_id]; packet_duration = end-start; if( start < end ) { seqno_diff = pkt_seqno[packet_id]-last_seqno; delay_diff = packet_duration - last_delay; if ( seqno_diff == 0 ) { jitter = 0; } else { jitter = delay_diff/seqno_diff; } printf("%f %f\n",start, jitter); last_seqno = pkt_seqno[packet_id]; last_delay = packet_duration; } } } 21

22 Analysis 2: Jitter(Cont.) ~$ awk jitter.awk out.tr > jitter.txt

23 Analysis 3: Packet Loss In the transmission, some of the packets may be lost due to the overflow of the queue Loss = Packets_Sent - Packets_Recieve r d End Time s2 Start Time In this example, we calculate the packet loss for the cbr traffic via udp transmission 23

24 Analysis 3: Packet Loss(Cont.) BEGIN { fsdrops = 0; numfs = 0; } { action = $1; time = $2; from = $3; to = $4; type = $5; pktsize = $6; flow_id = $8; src = $9; dst = $10; seq_no = $11; packet_id = $12; if ( from == 1 && to == 2 && action == "+" ) { numfs++; } if ( flow_id == 2 && action == "d" ) { fsdrops++; } } END{ printf("number of packets sent:%d lost:%d\n",numfs, fsdrops); } 24

25 Practice 1: Throughput To calculate the average throughput of the cbr traffic between node 2 and node 3 Average Throughput = Total Recieved Bytes / Elapsed Time Once node 3 recieve a packet, print out the real-time thoughput 25

26 Figure Output A picture paints a thousand words In a paper, figures(plots) are always the essential parts of the simulation and analysis section Tools for figure drawing Matlab Mathematica GNUplot 26

27 GNUplot Portable command-line driven graphing utility Support Linux, Windows, Mac OS... It allows scientists and students to visualize mathematical functions and data Supports many types of plots in either 2D and 3D. Installation in Ubuntu from source sudo apt-get install gnuplot 27

28 How to draw a figure Enter the GNUplot model ~$ gnuplot Draw a plot gnuplot > plot delay.txt To To denote denote the the gnuplot gnuplot model model The The command command for for drawing drawing The The file file name name 28

29 Result from the GNUplot 29

30 Commands in GNUplot (1) Set Axis Range Step Example For x axis gnuplot > set xtics -10,1,10 gnuplot > plot sin(x) Showing range gnuplot > set yrange [-2:2] gnuplot > plot sin(x) ` ` 30

31 Commands in GNUplot (2) Show grid gnuplot > set grid gnuplot > plot sin(x) 31

32 Commands in GNUplot (3) Labels title title ylabel ylabel label label arrow arrow xlabel xlabel gnuplot > set title CBR Delay gnuplot > set xlabel Simulation Time (s) gnuplot > set ylabel Delay (s) gnuplot > unset key gnuplot > set label constant delay = sec at 0.1,0.05 gnuplot > set arrow from 0.5,0.05 to 0.5,0.04 gnuplot > plot delay.txt with linespoints 32

33 Commands in GNUplot (4) points impulses Styles lines points linespoints impulses dots steps errorbars lines steps 33

34 Command in GNUplot (5) Output #set the picture format gnuplot > set terminal png #set the output file name gnuplot > set output delay.png #draw the plot gnuplot > plot delay.txt with linespoints 34

35 GPL script It is inconvenient to input commands Typos make errors We may redraw the plot for many times Solution Write the GPL script as gpl file set title "CBR Delay" set xlabel "Simulation Time (s)" set ylabel "Delay (s)" unset key set label "constant delay = sec" at 0.1,0.05 set arrow from 0.5,0.05 to 0.5,0.04 set terminal png set output "cbr_delay.png" plot "delay.txt" with linespoints Run the script in the terminal ~$ gnuplot -persist delay.gpl 35

36 Questions? Thank you!