Hi, Recently I was running simulation of BCP on TOSSIM but observed some strange behavior in the network.
The setup is as follows: Number of nodes -- one root and 39 sensor nodes. Network topology -- I used TinyOS tools to build the link models, in which 40 nodes are randomly placed in a 20m*20m square Noise model -- using the first 105 lines of meyerheavy.txt for sake of saving real simulation time Traffic pattern -- each sensor generate data packet according to a poisson process and the average packet generation interval is 100 seconds. Simulation length -- each sensor generate 50,000 packets. I calculated the statistics that only 94% of all the packets (from all sensors) are delivered to the root. For the specific node 8, I checked the routes of all its packets and found out that among the lost packets generated by node 8, some of the packets are trapped in intermediate nodes and more of them are trapped in node 8. The number of trapped packets at node 8 is far more than the queue length of node 8, which is set to be 48. However, the debug output also does not indicate any of packet discarding event (I added a dbg line in the function conditionalFQDiscard() of forward engine ). Nor does the debug output show any of ERROR information (I have added ERROR and DiscardPacket to the simulation display channels). I assume that the function conditionalFQDiscard() is the only function responsible for discarding packets. Is this correct? Any thoughts, ideas or suggestions would be appreciated. Thanks! Best, Wei
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