[e2e] RED simulation problems

[MURSHEDM]

Hi all, 

Can anybody please explain the following result of ns-2 simulation using
ns-2?
I have a RED router that serves exactly one packet after receiving 5
packets because 5 sources are connected to it and they will send a bust
of 15 packets. For the first 5 packets (queue is empty) Router will
serve only one packet therefore in the queue there will be 4 packets,
before the next 5 packets arrive. Surprisingly at the end of serving one
packet trace data shows there are only 3 packets (But accordingly based
on my calculation and setting there will be 4 packets, nam simulation
also shows 4 packets in the queue!) It doesn't work only for the first
packet arrival for all the other situation it gives corrects expected
result. For example the last two lines of the result must be (a 0.014
0.01996 Q 0.014 4) not (a 0.047 0.01996
Q 0.047 4) I changed router service rate but still got same result. At
the beginning it always wrong trace. Can anybody please explain this to
me? How can I fixed it, any thoughts or suggestion? It's really urgent
please help me if you have any clue. Please send responses at
murshedm at uiu.edu 

a 0.014 0.002
Q 0.014 1
a 0.014 0.005996
Q 0.014 2
a 0.014 0.011984
Q 0.014 3
a 0.047 0.01996
Q 0.047 4


Thanks and regards

Murshed