[ns] queueing mechanism in ns

[Punyaslok Purkayastha <punya@pal.ece.iisc.ernet.in>]

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.