Network delay calculation
Network delay is calculated using the SYN - SYN/ACK - ACK packets. If you are not seeing any SYN, SYN-ACK and ACK packets, network delay cannot be calculated.
 
Note: If we later see an ACK to DATA that is faster than the TCP handshake shown in Figure 33, we would reduce the network delay to that faster time.
The time between a client sending a SYN and it receiving a SYN/ACK from the server provides the server network delay, and the time between the server sending a SYN/ACK to when the server receives this ACK from the client indicates the client network delay. This is shown in Figure 33.
 
Figure 33: Network delay calculations
Diagram of network delay calculationDiagram of network delay calculation