surya:/home/mani/tcptrace-manual> tcptrace -lr indica.dmp.gz
1 arg remaining, starting with 'indica.dmp.gz'
Ostermann's tcptrace -- version 6.4.5 -- Fri Jun 13, 2003
153 packets seen, 153 TCP packets traced
elapsed wallclock time: 0:00:00.128422, 1191 pkts/sec analyzed
trace file elapsed time: 0:00:19.092645
TCP connection info:
1 TCP connection traced:
TCP connection 1:
host a: 192.168.0.70:32791
host b: webco.ent.ohiou.edu:23
complete conn: yes
first packet: Thu Aug 29 18:54:54.782937 2002
last packet: Thu Aug 29 18:55:13.875583 2002
elapsed time: 0:00:19.092645
total packets: 153
filename: indica.dmp.gz
a->b: b->a:
total packets: 91 total packets: 62
. . . . . .
. . . . . .
throughput: 10 Bps throughput: 94 Bps
RTT samples: 48 RTT samples: 47
RTT min: 74.1 ms RTT min: 0.1 ms
RTT max: 204.0 ms RTT max: 38.8 ms
RTT avg: 108.6 ms RTT avg: 8.1 ms
RTT stdev: 44.2 ms RTT stdev: 14.7 ms
RTT from 3WHS: 75.0 ms RTT from 3WHS: 0.1 ms
RTT full_sz smpls: 1 RTT full_sz smpls: 1
RTT full_sz min: 79.5 ms RTT full_sz min: 0.1 ms
RTT full_sz max: 79.5 ms RTT full_sz max: 0.1 ms
RTT full_sz avg: 79.5 ms RTT full_sz avg: 0.1 ms
RTT full_sz stdev: 0.0 ms RTT full_sz stdev: 0.0 ms
post-loss acks: 0 post-loss acks: 0
For the following 5 RTT statistics, only ACKs for
multiply-transmitted segments (ambiguous ACKs) were
considered. Times are taken from the last instance
of a segment.
ambiguous acks: 1 ambiguous acks: 0
RTT min (last): 76.3 ms RTT min (last): 0.0 ms
RTT max (last): 76.3 ms RTT max (last): 0.0 ms
RTT avg (last): 76.3 ms RTT avg (last): 0.0 ms
RTT sdv (last): 0.0 ms RTT sdv (last): 0.0 ms
segs cum acked: 0 segs cum acked: 0
duplicate acks: 0 duplicate acks: 0
triple dupacks: 0 triple dupacks: 0
max # retrans: 1 max # retrans: 0
min retr time: 380.2 ms min retr time: 0.0 ms
max retr time: 380.2 ms max retr time: 0.0 ms
avg retr time: 380.2 ms avg retr time: 0.0 ms
sdv retr time: 0.0 ms sdv retr time: 0.0 ms
o The ack packet has the biggest ACK (acknowledgment number) ever seen.
o The ack should be pure (carry zero tcp data payload).
o The advertised window carried in the ack packet should not change from the
last window advertisement.
o There must be some outstanding data.
Note : older versions of tcptrace (until version 6.4.2) used a legacy algorithm using just the first condition amongst the four listed above, to treat an ack as duplicate ack. This older behavior may be emulated (if necessary at all) with the --turn_off_BSD_dupack option.
The raw RTT samples found can also be dumped into data files with the -Z option as in
tcptrace -Z file.dmp
This generates files of the form a2b_rttraw.dat and b2a_rttraw.dat (for both directions of the first TCP connection traced), c2d_rttraw.dat and d2c_rttraw.dat (for the second TCP connection traced) etc. in the working directory. Each of the datafiles contain lines of the form :
seq# rttwhere seq# is the sequence number of the first byte of the segment being acknowledged (by the ack packet that contributed this RTT sample) and rtt is the RTT value in milli-seconds of the sample. Note that only valid RTT samples (as counted in the RTT Samples field listed above) are dumped.