Response Time calculation

Let us consider the illustration below:

1 SYN ->
2 SYN ACK <- (Server Network Delay)
3 ACK -> (Client Network Delay)
4 DATA -> (Client Response Time)
5 ACK <- (Network Delay)
6 DATA <- (Server Response Time)
7 ACK -> (Network Delay)
8 RST ->

NETWORK DELAY:
Network Delay is calculated as shown below:

Server Network Delay = 2 - 1.
Client Network Delay = 3 - 2.

If we later see an ACK to DATA that is faster than the TCP handshake noted above, we would reduce the network delay to that faster time. For example, if the result of 5 - 4 or 7 - 6 is lower than 2 - 1 and 3 - 2 respectively, then we would take the lower value to represent network delay.

NETWORK ROUNDTRIP:
Roundtrip is calculated as:

Server Network Delay + Client Network Delay = Network Roundtrip.

RESPONSE TIME:
Response Time is calculated as shown below:

Client Response Time = 4 - 3.
Server Response Time = 6 - 5.

DELAY TIME:

Time between first data packet sent by the server till the last packet sent before a client request.