[ns] Pairing a send and a corresponding ack - 2

[Meera Jayaram <meera_jayaram2001@yahoo.com>]

Hi folks,

I posted this query quite sometime back and could not
get an answer which would help me proceed.

Hence, I will try to explain my question again in more
detail. I hope someone can point me in the right
direction this time.

I am trying to find out if there is a way to pair the
send/forward events to their corresponding       
acknowledgements. I am doing a tcp based wireless
simulation run where I am trying to find the various
paths followed between source and destination for each
and every flow and also for how long each of these
paths lasted. 

I am kind of stuck at this stage where I am trying to
pair the ack with the send. It seems
that the ch->uid()(packet Id) and sequence
number(th->seqno_) have no relation execpt that they
form an increasing sequence.

When there is a retransmission due to timeout, we have
a new packet Id and seqno for this retransmitted
packet. Is there any way to find the original packet
Id and seqno of the packet corresponding to which the
retranmission is taking place (i.e what is the packet
Id or sequence number corresponding to the original
data packet for which this retransmission is taking
place!) Even if its not possible to get this info by
looking at the trace, can I determine this from some
part of the source code??

The reason I need this is because my application needs
to determine the amount of time for which a particular
path lasted since I am measuring the quality of a
protocol in the mobile simulation. Hence it is very
important that I detect the retransmissions and the
time at which the paths changed correctly. I have
examined the sources tcp.h, cmu-trace.h etc and I
cannot seem to find where exactly the following
information can be obtained.

Eagerly anticipating some help.

Thanks in advance.

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