Re: Measure the latency for a specific throughput/datarate method
- To: iperf-users --at-- dast.nlanr.net
- Subject: Re: Measure the latency for a specific throughput/datarate method
- From: "Tiago Junqueira" <tiago.junkeira --at-- gmail.com>
- Date: Tue, 19 Jun 2007 14:48:01 +0200
- Content-disposition: inline
- Content-transfer-encoding: 7bit
- Content-type: text/plain; charset=ISO-8859-1; format=flowed
- Dkim-signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=ERxyggsKiyX8iGzBikA+9x1ot5BCK8oyMpvYfpkdJWksb2yiWy0znEqKD94XcQho9pjkro6I5GbTXVLnVr8nk/PdtS8yZdmBjhdNL54gWI3fZSg6olwO0FHDO6c/mGKNAD3hk+gHaiotPl1k0mrXtq0wjFelTRqKOPUYnR4uAHs=
- Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=qtBA73gdCDamvcA+KOzJZslWIyqt+6xFOQPo5GR8jzOZg8kQDrnWNXUxmnZ9B69nE6f9dGJJyzyWIq6yA+fa2PrU5siZZa8rZcMqHlbdq3mc7vl2csbHaczpIQ5d8oYRNTN5PcMsj/14IqB5bh+swSSQboPYvwsTOhlVdof1X6E=
- In-reply-to: <4672A7AD.3000402@internet2.edu>
- References: <4bb1b4060706141840q4a5ce963qb6249a4d67166169@mail.gmail.com> <4672A7AD.3000402@internet2.edu>
- Reply-to: iperf-users --at-- dast.nlanr.net
- Sender: owner-iperf-users --at-- dast.nlanr.net
Hi Jeff,
Thanks for the telling me about the program thrulay. I'll test it
today. About the other question about the jitter, can you help me?
Iperf uses the following formula to calculate the instantaneous
Jitter:
# // TODO functionalize this
# // from RFC 1889, Real Time Protocol (RTP)
# // J = J + ( | D(i-1,i) | - J ) / 16
# transit = mPacketTime.subSec( sentTime );
# if ( lastTransit != 0.0 ) {
# deltaTransit = transit - lastTransit;
# if ( deltaTransit < 0.0 ) {
# deltaTransit = -deltaTransit;
# }
# mJitter += (1.0/16.0) * (deltaTransit - mJitter);
# }
# lastTransit = transit;
But it seems that the last samples have more weight than the earlier
ones, so if the Jitter before the last is high like:
J(Last)=J(Last-1)+(|D(i-1,i)|-J(Last-1))/16, the J(Last) will be high.
I was making mistake while taking the J(Last) as the overall jitter,
but it can't be in this way. Do you know how Iperf makes the average
of all the Jitter[i]?
Sorry to mess you about this question
kindly and thanks in advance, Tiago Junqueira
Student