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how to measure network and server latency

asked 2017-11-15 05:09:40 +0000

samir gravatar image

I'm capturing data from client and server port. i want to calculate network latency by deducting server and client side system process

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answered 2017-11-15 07:10:00 +0000

updated 2017-11-15 08:49:47 +0000

The easiest way is: In every TCP Session the iRTT will be calculated. As it measures the time between the syn and the syn, ack. So we can call this the RTT or latency of the network for that session.

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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.

Jasper gravatar imageJasper ( 2017-11-15 08:13:54 +0000 )edit

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.

samir gravatar imagesamir ( 2017-11-15 14:42:09 +0000 )edit

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.

grahamb gravatar imagegrahamb ( 2017-11-15 14:45:44 +0000 )edit

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.

Christian_R gravatar imageChristian_R ( 2017-11-15 16:55:55 +0000 )edit

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Asked: 2017-11-15 05:09:40 +0000

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Last updated: Nov 15