[ns] Jitter Calculation

[Mohammad Haseeb Zafar]

Hi
Further to my previous email, anyone who has awk or perl code to calculate jitter.
I would really appreciate your help in this regard.
Cheers
Haseeb

________________________________

From: Mohammad Haseeb Zafar
Sent: Mon 16/06/2008 2:57 PM
To: ns-users at ISI.EDU
Subject: Jitter Calculation


Hello all

I wanted to know if anyone has used below awk script to calculate jitter. We have 2 different values of jitter, and the calculations in the script dont explain me fully which jitter you would look for finding out whats the jitter for that particular communication.
Can someone please help me for this?

Cheers

Haseeb

#  ============================== jitter.awk ============================
  BEGIN {
       num_recv=0
 }
  {
 # Trace line format: normal
 if ($2 != "-t") {
  event = $1
  time = $2
  if (event == "+" || event == "-") node_id = $3
  if (event == "r" || event == "d") node_id = $4
  flow_id = $8
  pkt_id = $12
  pkt_size = $6
  flow_t = $5
  level = "AGT"
 }
 # Trace line format: new
 if ($2 == "-t") {
  event = $1
  time = $3
  node_id = $5
  flow_id = $39
  pkt_id = $41
  pkt_size = $37
  flow_t = $45
  level = $19
 }
   # Store packets send time
 if (level == "AGT" && sendTime[pkt_id] == 0 && (event == "+" || event == "s") && pkt_size >= 512) {
  sendTime[pkt_id] = time
 }
   # Store packets arrival time
 if (level == "AGT" && event == "r" && pkt_size >= 512) {
  recvTime[pkt_id] = time
  num_recv++
 }
}
  END {
 # Compute average jitter
 jitter1 = jitter2 = tmp_recv = 0
 prev_time = delay = prev_delay = processed = 0
 prev_delay = -1
 for (i=0; processed<num_recv; i++) {
  if(recvTime[i] != 0) {
          tmp_recv++
   if(prev_time != 0) {
    delay = recvTime[i] - prev_time
    e2eDelay = recvTime[i] - sendTime[i]
    if(delay < 0) delay = 0
    if(prev_delay != -1) {
     jitter1 += abs(e2eDelay - prev_e2eDelay)
     jitter2 += abs(delay-prev_delay)
    }
    prev_delay = delay
    prev_e2eDelay = e2eDelay
   }
   prev_time = recvTime[i]
  }
  processed++
 }
}
  END {
  
       printf("Jitter1 = %.2f\n",jitter1*1000/tmp_recv);
       printf("Jitter2 = %.2f\n",jitter2*1000/tmp_recv);
}
  function abs(value) {
 if (value < 0) value = 0-value
 return value
}