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Method to Measure the Queue Size for this topology

  • From: Tiago Junqueira
  • Date: Tue Jun 19 21:07:25 2007
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Hi ,

 I have this configuration (SS-Wimax Subscriber Station and BS-Wimax
Base Station)):
(PC1)----100mbs---(SS)----3mbs----(BS)----100mbs----(PC2)

When i measure the RTT with the ping command from the PC1 to the PC2,
i'm measuring approximately the packet service time of the station SS
= 1/u2, and also the time of the BS when the reply comes, that can be
more or less 1/u2. The time of processing from the computers in not
significant.
 If i use iperf to send a flow of 6mbs from the PC1 to the PC2, the
Wimax queue of the SS will built up and if i run the ping command with
the same packet size, and with 1 second of interval (that is not
significant when compared to the iperf), the time of processing of the
SS=X.(1/u2) because the packet sent by ping will reach the last place
of the queue. When it return has 1/u2 additional from the BS.
 So if I divide, I'll get X, that is approximately the queue size of
the SS. Do you think that it gives a notion about the size of the
buffer of the SS?

 By the way, i didn't use thrulay, because the delay is high, maybe
because of the time synchronization between the PC1 and PC2. Is easy
to synchronize the both computers, having one as server and another
receiving the synchronization?

 kindly, and thanks for the precious help given
Tiago Junqueira