I want to make a lab experiment to measure the firewall (a hardware) latency. This firewall can do Deep Packet Inspection (DPI) on some industrial protocols (you can consider as TCP payload inspection). Hence, I want to measure the firewall's latency when inspecting the payload.
Assume I have a sender PC and a receiver PC. The firewall is connected in between. I can build a packet generator on the sender, and use wireshark installed on each PC to confirm whether the packet pass the firewall or not.
Hence, what is the effective way to measure the latency (e.g. xxx ms delay on average by comparing without firewall) that the firewall inspects the packets? (such as existing software)