how to measure network and server latency

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Note: that's not for every TCP connection, only those with a complete handshake.The iRTT field can be found in the TCP header at the bottom if the handshake was complete.

Thanks for Explation christian

this rtt also include the processing time taken by far end server who suppose to send the acknowledge. so let me put this way 1 i'm capturing from source 2 also capturing packet on destination

now what i wanted to know is how much network latency is contributing in total RTT.

example A-> send packet to B, B process the packet and sent ack to A. now A got ack from B with rtt which include data processing time taken by B. So rtt would not be my actual network latency. Network latency =total rtt minus data processing and ack time taken by B.

How we would get this with wirehshark. actual network latency.

You would have to subtract the delta time between incoming and response on B as that's the "processing" time on B. There's no way to do that directly in Wireshark between the two captures.

Hello if you have captured the 3-way Handshake and the iRTT has been calculated you have more or less the network response time. As we assume that the only the stack is involved in generating the SYN,ACK we can assume that this is more or less the network round trip time. So the network delay will be half of the RTT. Otherwise the RTT by ACK measuring is sometimes harder as something like Delayed ACK and so on comes into play.

Nice article about performance measuring by packet analysis