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Joe_Hsy_45207's avatar
Joe_Hsy_45207
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Nov 09, 2007

Anyone knows of/used TCP::rtt (smooth TCP round trip time)?

 

Hi,

 

 

I was wondering if anyone has any experience with or knows of the algorithm used with the TCP::rtt metric which is supposed to return the "smoothed round-trip time estimate for a TCP connection"?

 

 

I've done some experimentation and sometimes the rtt is zero - which I assume means that there hasn't been enough data for the estimate? It is also difficult to figure out how the smoothing algorithm works and how far back in time does the estimate go. It also seems to be less accurate in small latency situations.

 

 

Any help on this would be greatly appreciated!

 

 

//Joe
application delivery
dev
devops
iRules
  • Joe_Hsy_45207's avatar
    Joe_Hsy_45207
    Icon for Nimbostratus rankNimbostratus
    Nov 13, 2007
    A follow-up to that thread is that is it possible to use [IP::stats pkts in] and [IP::stats pkts out] to guage how accurate the TCP::rtt time is? The thread seem to imply that the more packets have been exchanged, the more accurate the time becomes. So, if we ignore the data until say 10 packets have been exchanged?

     

     

    Do both inbound and outbound packets affect this or just on direction?

     

     

    Thanks!

     

     

    //Joe