I'm making some simple simulations for long fat networks - the networks with 
large bandwidth delay product. I'm working on simple Y shaped network, with two 
senders, chokepoint router and one receiver. My goal is to simulate networks 
with 100Gbps bandwidths and 100ms delays (all three links have these settings). 
If I calculated correctly:

BDP = 100Gb/s * 0.1s = 10Gb / 8 = 1 250 000 B

So there could be roughly 1 250 000 bytes in transit through the network (even 
more if the queue is full). The problem I'm having is the packets are going 
through queues on senders. If I run my simulation in nam, I can see packets 
dropping from the nodes which are actually sending the data (they have TCP and 
FTP attached to them) because the queues are too small. I'm dealing with this 
problem by setting larger queues. But on networks with such large BDP, the 
queues must be 1GB in size (on sender nodes) to avoid the drops in the places 
where they should not even happen, which slows the simulation down to a halt.

Does anybody know how to bypass the sending queues in this matter? Or any other 
solution to this problem? Please, this is very important to me and I'm getting 
desperate with it. Thanks for any information.



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