calculating Bandwidth delay product

Hi,
Please guide me regarding some doubts on calculating the BDP

I am using the following formula,

BDP = bandwidth * RTT
= 100 mbs * 67 ms
= 13107200 byte * .067 sec
= 878182.4 bytes/sec
= 857.6 KBytes
= 860 KBytes approx

Based on that , I have done the following changes.

sysctl -w net.core.ipv4.rmem = 4096 87380 878182
sysctl -w net.core.ipv4.wmem = 4096 87380 878182


sysctl -w net.core.wmem_max = 878182
sysctl -w net.core.rmem_max = 878182

Is the following are corrects. After doing these settings , I am
receiving a transfer rate of 70 mbs using iperf , a TCP and UDP
performance measurement tool. But if i double
the value of BDP i.e if I use 1600 Kbytes of BDP , then I am
reaching the bandwidth
of 97 mbs .
My question is . is it O.K to assign a greater value (as twice
as ) , then the calculated
BDP . Or the RFCs does not allow this.

Also another doubt which bandwidth we should consider.

My speed of NIC is 1000 mbs per second, speed of the switch is
100mbs and
the leased line link which connects us to other networks is
dedicated 100mbs.
The leased line link is not shared.So , i am getting 100mbs.
Now, which bandwidth should i Consider. the speed of NIC , the speed
of switch
or the speed of leased line.
Also , regarding the RTT . Suppose I am communicating with various
links that has
RTTs of 67 ms , 56 ms , 47 ms. Which RTT should I consider.


Please Guide me.