RTT in nanoseconds
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Thread: RTT in nanoseconds

  1. #1
    Join Date
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    RTT in nanoseconds

    Hi everyone. I'm new to socket programming so sorry if this is a noob question.

    Nway, is there a way to ping an access point, given that i know it's IP address, and get the RTT in nanoseconds, instead of miliseconds?

  2. #2
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    Re: RTT in nanoseconds

    Divide?

    http://www.calculateme.com/Time/Nano...lliseconds.htm
    RTT is internal to TCP; there is no way for an application to get the value. Instead, you should do the same thing TCP does: arrange to exchange a few messages, compute your own estimate of the round trip time, then divide that by 2, and add it to the clock before sending the time.
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  3. #3
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    Re: RTT in nanoseconds

    Depending on what OS you are using, you might or might not be able to get super accurate times.

    On MS, you can use QueryPerformanceFrequence as a high resolution timer.

  4. #4
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    Re: RTT in nanoseconds

    But seriously, why do you think you need nanosecond precision in RTT? RTT is known to deviate significantly from segment to segment, and in fact the deviation is so significant that most stacks calculate the retransmission timeout based also on the deviation in RTT, not simply the RTT alone.

    Most implementations are happy with an estimate of RTT in the millisecond-range precision. You want something one million times more accurate. It would be helpful if you explained why.

    Mike

  5. #5
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    Re: RTT in nanoseconds

    Quote Originally Posted by MikeAThon
    But seriously, why do you think you need nanosecond precision in RTT? RTT is known to deviate significantly from segment to segment, and in fact the deviation is so significant that most stacks calculate the retransmission timeout based also on the deviation in RTT, not simply the RTT alone.

    Most implementations are happy with an estimate of RTT in the millisecond-range precision. You want something one million times more accurate. It would be helpful if you explained why.

    Mike
    Ok. I might not really need nanosecond precision for this. is jst that i need to calculate de average RTT from a laptop to an access point and i can't have 0ms as a result.

    The laptop and the access point will be only a few meters away from each other. Therefore i think that millisencond estimation won't be enough.

    Thanx for the replies btw.
    Last edited by iStriker; October 25th, 2007 at 11:05 AM.

  6. #6
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    Mar 2012
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    Re: RTT in nanoseconds

    hi ,

    i'm doing project on positioning using time of arrival techniques. So i need round trip time (RTT) in nanoseconds in order to calculate time of arrival from access point to laptop..

  7. #7
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    Aug 2013
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    Re: RTT in nanoseconds

    Quote Originally Posted by iStriker View Post
    Ok. I might not really need nanosecond precision for this. is jst that i need to calculate de average RTT from a laptop to an access point and i can't have 0ms as a result.

    The laptop and the access point will be only a few meters away from each other. Therefore i think that millisencond estimation won't be enough.

    Thanx for the replies btw.

    Hi istrike;
    Did you calculate the RTT in nanoseconds... I also want to calculate RTT in micro or nanoseconds... if you have solve the issue please reply with the code..

    Thanks..

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