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I have a connection with four nodes, A, B, C, D.

I want to send a large file from A to D and want to calculate the delay bandwidth product.

The bandwidth and delay, respectively, of each link is as follows:

A-B : 2gb/s, 10ms B-C : 2mb/s, 10ms C-D : 2gb/s, 10ms

My question is, to calculate the DBP, do I use the slowest link or add up all the links' bandwidths? That is, is my bandwidth product (4gb + 2mb)/s * 60ms or simply 2mb/s * 20ms? (Using the DBP formula of bytes/s * RTT).

My reasoning is that B-C will almost always be full, and the transfer of packets through link A-B and C-D are almost instantaneous, so I should just use the numbers of the B-C link. Is this correct?

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1  
Min bw * sum of delays – Ron Trunk Apr 4 '14 at 3:25
    
@Ron Would it be min bw * (2 * sum of the delays) for round trip time? – Public Display Name Apr 4 '14 at 3:50
1  
Are those values one way delay or the RTT between these nodes? You need to use the minimum BW in transit as that will always be the bottleneck. If you have a hop with only 2 Mbit/s that will slow down all the transfers even if you have high speed links before and after that. – Daniel Dib Apr 4 '14 at 4:30
1  
Yes, of course. Forgive my senior moment. 2* BW-min * sum of delays) – Ron Trunk Apr 4 '14 at 12:21

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