It can be done either manually or with a script, but I do not recommend it because there are so some many "what if?"
- The integrity of the timestamps in both files need to verify. Timestamps can be affected if the computer capturing packets is doing offloading, background applications running, slow CPU or has high CPU utilization.
- Both devices need a clock that traceable back to a reliable clock source (e.g., NTP). BTW, there is jitter on NTP. An example if the clocks are off by 500ms, your timestamp will be off by 500ms. You can always adjust the timestamps on the file, but the clocks must be verified before every capture.
- Out-of-order and dropped packets
- Graph throughput with I/0 graph
