flowmonitor and bulksendapplication send size

[Lakshmi Krishnaswamy]

Hello all,

Hope you all are doing great. I have some doubts regarding the output reported by flowmonitor and regarding my understanding of it, and assistance would be greatly appreciated!

I am using BulkSendApplication to send flows, of SendSize = 1400 ( packet size ) and the MaxBytes = flow size , where flows are 1KB or 1MB in size.

for a flow that is 1000 bytes, given these settings, I would be expecting it to be sent via a single packet (MTU size is 1500 bytes ).Is this a valid expectation or am I missing out on something else ?

On observing the results of flowmonitor, the RxBytes and TxBytes are 1160 and the TxPackets and RxPackets are 3.

Any help with understanding this would be greatly appreciated. Thank you so much once again! 

[Deepak K]

Hi there! You are correct when you expect that a single data packet would be transferred. However, the process of establishing and destroying a TCP connection between two nodes involves other non-data packets to be sent and received, such as SYN, SYN-ACK (during connection establishment) and FIN (during connection termination). All these non-data packets combined with the single data packet result in the value of 3 that you observe.

Hope this helps.

[Lakshmi Krishnaswamy]

Hi thank you so much for your prompt response ! Oh yes definitely - thank you so much! I was wondering, why even few other packets of the same size, this was occurring - realized that then even they were using new sockets and hence require new TCP connection establishments. 

Thank you so much once again, this definitely helps