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EvalVid Delay

EvalVid Delay in data networks is generally the round trip delay.The total time that it takes for this chunk of information, commonly called a packet, to travel end-to-end is called network delay.

Procedure to calculate  EvalVid delay:

EvalVid delay criteria

dend-end= N[ dtrans+dprop+dproc]

where

dend-end= end-to-end delay

dtrans= transmission delay

dprop= propagation delay

dproc= processing delay

dqueue= Queuing delay

N= number of links (Number of routers + 1)

EvalVid Delay Process

  • The sendtime_ field is to record the packet sending time.
  • It can be used to measure end-to-end delay.
  • The script extracts the end-to-end delay, but it can be modified to extract the inter-frame jitter at the sender or receiver or the cumulative jitter.
  • It calculates the PDF (probabilty density function) and CDF (cumulative distribution function) of the delay.
  • Lost packets/frames get a delay of 0. Thus, the start of the CDF-lines is the percentage of lost frames/packets.

Sample EvalVid Delay code

. evalvid.conf
for mode in fx f0 p0; do
  count=0
  echo -n "time_[s]" > delay"_"$mode.txt
  for l in $RESDIR/$mode/delay*.txt; do
    printf "\tPDF_`basename $l .txt` CDF_`basename $l .txt`" >> delay"_"$mode.txt

    [ $count == 0 ] && awk '{print $3}' < $l | hist - $T1_DELAY $T2_DELAY $T_STEPS | awk '{print $1}' > time.txt
    awk '{print $3}' < $l | hist - $T1_DELAY $T2_DELAY $T_STEPS | awk '{print $2,$3}' > tmp.txt
    [ $count != 0 ] && cp d"_"$mode.txt time.txt
    paste time.txt tmp.txt > d"_"$mode.txt
    count=$((count+1))
    printf "%8d %s\n" $count $l
  done
  echo "" >> delay"_"$mode.txt
  mv delay"_"$mode.txt $RESDIR
  cat d"_"$mode.txt >> $RESDIR/delay"_"$mode.txt
  rm d"_"$mode.txt time.txt tmp.txt
done

Download sample Ns2 program on how to calculate Evalvid delay in a network which causes round trip delay in a network.


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