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measure-jitter.awk：源码内容

							#This program is used to calculate the jitters for CBR
# jitter ＝((recvtime(j)-sendtime(j))-(recvtime(i)-sendtime(i)))/(j-i),  j > i
 BEGIN {
# Initialization
     highest_packet_id = 0;
}
{
   action = $1;
   time = $2;
   #from = $3;
   #to = $4;
   type = $7;
   pktsize = $8;
   #flow_id = $8;
   src = $10;
   dst = $11;
   #seq_no = $11;
   packet_id = $6;
 
   if ( packet_id > highest_packet_id ) {
           highest_packet_id = packet_id;
        }
 
#Record the transmission time
   if ( start_time[packet_id] == 0 )  {
           # Record the sequence number
           pkt_seqno[packet_id] = seq_no;
           start_time[packet_id] = time;
   }
 
#Record the receiving time for CBR (flow_id=2)
   if ( type=="cbr" && action != "d" ) {
      if ( action == "r" ) {
             end_time[packet_id] = time;
      }
    } else {
      end_time[packet_id] = -1;
   }
}                                                       
END {
        last_seqno = 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 %fn", start, jitter);
               last_seqno = pkt_seqno[packet_id];
               last_delay = packet_duration;
       }
    }
}

						