about calculate TCP performance

Hi, I'll try to give you some guidance. I'll assume that you are using Wireshark 2.

TCP Throughput

I'm not completely sure what you mean by this but if you want to know the data rate on a particular TCP connection you can do this by selecting a particular TCP stream. As an example I'll use TCP Stream 0 to an SMB file server (on TCP Port 445):

• Go to Menu > Statistics > IO Graph
• Click on the + button in the bottom left of the graph window
• Name the new plot TCP Stream 0 Tx
• In the Display Filter field enter tcp.stream==0 && tcp.dstport==445
• In the Y Axis field select Bits/s
• Check the box next to the name to display the result (uncheck all plots)
• Click on the + button in the bottom left of the graph window
• Name the new plot TCP Stream 0 Tx
• In the Display Filter field enter tcp.stream==0 && tcp.srcport==445
• In the Y Axis field select Bits/s
• Check the box next to the name to display the result

Capacity

Not sure what you mean. You could measure apparent capacity by plotting Bits/s in the Tx and Rx directions and looking for the maximum value.

Round Trip Time

I think most people measure this by looking at the delta between a SYN and a SYN/ACK. You can do this by sorting the trace by tcp.stream, filtering for packets with the SYN flag set and adding the column Time delta from previously displayed frame. Export the Summary Line into CSV and then fiddling around with the CSV in Excel.

A much quicker way is to use the TRANSUM plugin - see http://www.tribelab.com/transum:

• Start Wireshark with TRANSUM
• Open the trace file
• Set a display filter tcp.flags.syn==1 && transum
• Expand the TRANSUM RTE Data tree in the packet detail frame
• Right click on APDU Response Time and Apply as Column
• You should now see the SYN to SYN/ACK delays and hence the nominal RTT

I'll deal with the remaining points in little later - have to get off the train I'm on.