Re: [ns] queueing mechanism in ns

["Bilgin Metin" <bilginx@boun.edu.tr>]

Hi,
I think the last column gives packet id. Thus, in trace file we should
compare two lines which is beginning with different sign "+" and "-" but
which has  the same packet id. In the beginning of a simulation , because
the queue is empty, the queuing delay   is zero and the line with  the same
packet id is next to other one. .  Usually after 3 second later from
beginning of a simulation, there are a lot of lines  of other packets
between the   lines with the same packet id. Hence, delay will not probably
zero.

Sincerely,
Bilgin Metin


----- Original Message -----
From: "Punyaslok Purkayastha" <punya@pal.ece.iisc.ernet.in>
To: <l.wood@eim.surrey.ac.uk>
Cc: <ns-users@ISI.EDU>
Sent: Thursday, July 27, 2000 11:47 PM
Subject: [ns] queueing mechanism in ns


>
> hi,
>
> i am not quite sure i understand the exact queueing and delay mechanisms
> of ns. i am employing a tcp source going through  a
> single link. the first two lines of output in my trace file are
>
> + 0 0 1 tcp 750 ------- 1 0.0 1.0 0 0
> - 0 0 1 tcp 750 ------- 1 0.0 1.0 0 0
>
> now my tcp packets should suffer a transmission delay of .6 ms. however
> the output shows that the packet suffers no delay at all ( it gets
> enqueued and dequeued at the same time).
>
> however note (at a later portion of the trace file)
>
> r 0.0206 0 1 tcp 750 ------- 1 0.0 1.0 0 0
>
> the propagation delay of my forward direction link is 20ms; so that i do
> get that the said tcp packet arrives at the receiving end 20ms+.6ms later.
>
> i am perplexed by what is going on.
>
> Punyaslok.
>
>