M. Dahshan - TCOM52721 TCOM 5272 Telecomm Lab Dr. Mostafa Dahshan OU-Tulsa 4W 2 nd floor

M. Dahshan - TCOM52722 References  Awk – A Tutorial and Introduction  NS by Example nile.wpi.edu/NS/ nile.wpi.edu/NS/

M. Dahshan - TCOM52723

4 Awk utility  Awk is an excellent filtering and reporting utility  A pseudo-C interpreter  Same C arithmetic  Supports associative arrays (array index can be a variable of any type)

M. Dahshan - TCOM52725 Awk – Basic Structure  pattern { action }  pattern specifies when action is performed  Awk is line oriented  Default pattern matches every line  Two other important patterns BEGIN END

M. Dahshan - TCOM52726 Awk – Basic Structure  Example on an NS trace file cbr cbr r cbr BEGIN {print “Time\tSequence Number”} {print $2”\t”$11} END {print “DONE”}  Output TimeSequence Number DONE

M. Dahshan - TCOM52727 Calculating Packet Delay BEGIN { # simple awk script to generate end-to-end # packet lifetime statistics # in a form suitable for plotting with xgraph # Lloyd Wood, July # highest_packet_id = 0; }

M. Dahshan - TCOM52728 Calculating Packet Delay { action = $1; time = $2; node_1 = $3; node_2 = $4; src = $5; flow_id = $8; node_1_address = $9; node_2_address = $10; seq_no = $11; packet_id = $12;

M. Dahshan - TCOM52729 Calculating Packet Delay if ( packet_id > highest_packet_id ) highest_packet_id = packet_id; # getting start time is not a problem, provided you're not starting # traffic at 0.0. # could test for sending node_1_address or flow_id here. if ( start_time[packet_id] == 0 ) start_time[packet_id] = time; # only useful for small unicast where packet_id doesn't wrap. # checking receive means avoiding recording drops if ( action != "d" ) { if ( action == "r" ) { # could test for receiving node_2_address or flow_id here. end_time[packet_id] = time; } } else { end_time[packet_id] = -1; }

M. Dahshan - TCOM Calculating Packet Delay 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("%d %f\n", packet_id, packet_duration); }

M. Dahshan - TCOM Calculate Average Delay  First, calculate packet delay  { #increment number of lines num_lines++; #sum the delay values #column 2 is the packet delay sum_delay=sum_delay+$2; } END {print sum_delay/num_lines}

M. Dahshan - TCOM Calculating Dropped Packets BEGIN{dropped=0} { action = $1; if(action=="d") dropped++; } END{print dropped}

M. Dahshan - TCOM Calculating Throughput  Throughput = total number of bytes received  BEGIN{dest=3} { action = $1; node2 = $4; packet_size = $6; if(action=="r" && node2=dest) throughput + = packet_size; } END{throughput}

M. Dahshan - TCOM Calculating Jitter  Jitter = difference between packet delays  First, calculate packet delay

M. Dahshan - TCOM Calculating Jitter BEGIN {old_delay=0.0;} { delay = $2; if(old_delay>0) jitter=delay-old_delay; else jitter=0.0; #if(jitter<0) jitter = -jitter; old_delay = delay; print $1 " " jitter; }

M. Dahshan - TCOM cat, grep, wc  We can simplify processing by doing some pre-filtering using grep  We can also do some quick calculations by combining multiple small commands  Take the output of a command as an input to the next command (pipes)

M. Dahshan - TCOM Print only CBR Traffic  grep cbr out.tr cbr cbr cbr cbr r cbr cbr cbr cbr cbr r cbr

M. Dahshan - TCOM Print CBR Traffic From 2 to 3  grep "2 3 cbr" out.tr cbr cbr cbr cbr cbr cbr cbr cbr r cbr cbr

M. Dahshan - TCOM Print Only Received Packets  grep ^r out.tr r cbr r cbr r cbr r cbr r cbr r cbr r cbr r cbr r cbr r cbr

M. Dahshan - TCOM Print CBR Received at Node 3  grep ^r out.tr | grep "2 3 cbr" r cbr r cbr r cbr r cbr r cbr r cbr r cbr r cbr r cbr r cbr

M. Dahshan - TCOM Calculate Dropped Packets!  grep ^d out.tr | wc –l 18

M. Dahshan - TCOM527222

M. Dahshan - TCOM Trace Analysis Example  Download the file Trace Analysis Example simple-trace.tcl simple-trace.tcl

M. Dahshan - TCOM Activity 1: Calculate Packet Delay  Use the provided packet delay script to calculate the delay for CBR traffic only!  Save the output to a file cbr_delay.txt  Commands: ns ns-simple-trace.tcl grep cbr out.tr | awk -f pkt_delay.awk > cbr_delay.txt

M. Dahshan - TCOM Activity 2: Calculate Jitter  Use the provided packet jitter script to calculate the delay for CBR traffic  Save the output to a file cbr_jitter.txt  Commands: awk -f jitter.awk cbr_delay.txt > cbr_jitter.txt

M. Dahshan - TCOM Activity 3: Plot Delay and Jitter  Use xgraph or gnuplot to plot the delay and jitter for CBR traffic on the same graph  For xgraph xgraph cbr_delay.txt cbr_jitter.txt

M. Dahshan - TCOM Activity 3: Plot Delay and Jitter  Using gnuplot  gnuplot gnuplot>set key left top Right noreverse enhanced box gnuplot>set xlabel "Packet ID" gnuplot>set ylabel "Delay and Jitter (sec)" gnuplot>plot “cbr_delay.txt" using 1:2 title “Packet Delay" with lines 1, “cbr_jitter.txt" using 1:2 title “Jitter" with lines 2

M. Dahshan - TCOM Activity 4: Stochastic Fair Queue  Edit the ns-sample-trace.tcl script  Change the queue type from DropTail to SFQ  Save as ns-sample-trace-sfq.tcl  Recalculate delay, jitter and plot the results (cbr_delay_sfq.txt, cbr_jitter_sfq.txt)  Discuss your findings

M. Dahshan - TCOM Activity 4: Random Early Detection  Edit the ns-sample-trace.tcl script  Change the queue type from DropTail to RED  Save as: ns-sample-trace-red.tcl  Recalculate delay, jitter and plot the results (cbr_delay_red.txt, cbr_jitter_red.txt)  Discuss your findings