Wireshark mailing list archives

Re: End to End VoIP delay calculation (Interarrival jitter)


From: capricorn 80 <cool_capricorn80 () hotmail com>
Date: Fri, 27 Nov 2009 23:17:10 +0000



 HI !
  I have checked that and didn't pay mention attention to it but now I have downloaded the aaa.pcap and working it. In 
this file all communication is from
Sender: 192.168.1.2 to Destination: 212.242.33.36
but in my case on 31 I am getting source 61.216.159 and destination 113.
31      24.685764       61.216.159.110      113.100.26.222      RTP          0.009784  Why its like that in my case ?
Regards,

Date: Fri, 27 Nov 2009 16:11:29 +0100
From: Lars.Ruoff () alcatel-lucent com
To: wireshark-users () wireshark org
Subject: Re: [Wireshark-users] End to End VoIP delay calculation      (Interarrival jitter)

Have you checked http://wiki.wireshark.org/RTP_statistics => How jitter
is calculated ?

Regards,
Lars

________________________________

      From: wireshark-users-bounces () wireshark org
[mailto:wireshark-users-bounces () wireshark org] On Behalf Of capricorn 80
      Sent: vendredi 27 novembre 2009 15:44
      To: wireshark-users () wireshark org
      Subject: Re: [Wireshark-users] End to End VoIP delay calculation
(Interarrival jitter)
      
      

       Hi !
      
        Thanks for your responses. @ martin.r.mathieson: I tried alot
to understand but may be I dont have much expertise in this case :(. 
        .Now I am doing like this that I have run wireshark on
computer and computer is synchronized with ntp server. I am looking for
interarrival calculation.
      
      This is my readings from wireshark: (The IP addresses i
mentioned is dummy one).
      
      113.100.26.222 is computer
      61.216.159.110 is asterisk server 
      
       No     Time            Source              Destination
Protocol     Delta time
      
------------------------------------------------------------------------
-------------------
       28    24.646137    113.100.26.222        61.216.159.110    RTP
0.031826
       Arrival Time: Nov 23, 2009 23:50:32.660458000
       Sequence number: 7867
       Timestamp: 365000
      
      
------------------------------------------------------------------------
--------------------
       29    24.656106    113.100.26.222        61.216.159.110    RTP
0.009969
       Arrival Time: Nov 23, 2009 23:50:32.670427000
       Sequence number: 7868
       Timestamp: 365160 
      
------------------------------------------------------------------------
--------------------
      
       30    24.675980    113.100.26.222        61.216.159.110    RTP
0.019874
       Arrival Time: Nov 23, 2009 23:50:32.690301000
       Sequence number: 3771
       Timestamp: 422060
      
------------------------------------------------------------------------
---------------------
       31    24.685764    61.216.159.110        113.100.26.222    RTP
0.009784 
       Arrival Time: Nov 23, 2009 23:50:32.700085000
       Sequence number: 3767
       Timestamp: 421420 
      
      
------------------------------------------------------------------------
----------------------
       32    24.695953    113.100.26.222        61.216.159.110    RTP
0.010189
       Arrival Time: Nov 23, 2009 23:50:32.710274000
       Sequence number: 7870
       Timestamp: 365480
      
      
------------------------------------------------------------------------
-----------------------
       33    24.704766    61.216.159.110        113.100.26.222    RTP
0.008813 
       Arrival Time: Nov 23, 2009 23:50:32.719087000
       Sequence number: 3768
       Timestamp: 421580
      
      
------------------------------------------------------------------------
-----------------------
      
       Please if you help me in telling that how can I calculated the
Interarrival jitter in steps in that case. I shall be very thanksful to
you.
      
      Regards,
      
      
      
      
      
________________________________

      Date: Thu, 26 Nov 2009 09:23:21 +0000
      From: martin.r.mathieson () googlemail com
      To: wireshark-users () wireshark org
      Subject: Re: [Wireshark-users] End to End VoIP delay calculation
      
      There is the RTCP roundtrip network propagation delay.  If the
necessary reports are present and properly formatted, there will be an
expert info item for any calculations that may be made. You will need to
enable this calculation in the RTCP dissector preferences.
      
      Here is the extract from RFC 3550, section 6.4.1, that describes
how the calculation should be done:
      
      
      delay since last SR (DLSR): 32 bits
            The delay, expressed in units of 1/65536 seconds, between
      
            receiving the last SR packet from source SSRC_n and
sending this
            reception report block.  If no SR packet has been received
yet
            from SSRC_n, the DLSR field is set to zero.
      
            Let SSRC_r denote the receiver issuing this receiver
report.
      
            Source SSRC_n can compute the round-trip propagation delay
to
            SSRC_r by recording the time A when this reception report
block is
            received.  It calculates the total round-trip time A-LSR
using the
      
            last SR timestamp (LSR) field, and then subtracting this
field to
            leave the round-trip propagation delay as (A - LSR -
DLSR).  This
      
      
      
      Schulzrinne, et al.         Standards Track
[Page 40]
      
      
      RFC 3550                          RTP
July 2003
      
      
            is illustrated in Fig. 2.  Times are shown in both a
hexadecimal
            representation of the 32-bit fields and the equivalent
floating-
      
            point decimal representation.  Colons indicate a 32-bit
field
            divided into a 16-bit integer part and 16-bit fraction
part.
      
            This may be used as an approximate measure of distance to
cluster
            receivers, although some links have very asymmetric
delays.
      
      
         [10 Nov 1995 11:33:25.125 UTC]       [10 Nov 1995 11:33:36.5
UTC]
         n                 SR(n)              A=b710:8000 (46864.500
s)
      
---------------------------------------------------------------->
                            v                 ^
      
         ntp_sec =0xb44db705 v               ^ dlsr=0x0005:4000 (
5.250s)
         ntp_frac=0x20000000  v             ^  lsr =0xb705:2000
(46853.125s)
           (3024992005.125 s)  v           ^
         r                      v         ^ RR(n)
      
      
---------------------------------------------------------------->
                                |<-DLSR->|
                                 (5.250 s)
      
         A     0xb710:8000 (46864.500 s)
         DLSR -0x0005:4000 (    5.250 s)
      
         LSR  -0xb705:2000 (46853.125 s)
         -------------------------------
         delay 0x0006:2000 (    6.125 s)
      
                 Figure 2: Example for round-trip time computation
      
      





      On Thu, Nov 26, 2009 at 2:48 AM, Martin Visser
<martinvisser99 () gmail com> wrote:
      

              As RTP in each direction is unacknowledged (you have a
unidirectional stream going each direction) there is no way to determine
end-to-delay from that. I think the best you can do is look at the SIP
request/response time as an estimate.

              Regards, Martin
              
              MartinVisser99 () gmail com
              
              
              
              On Wed, Nov 25, 2009 at 4:31 AM, capricorn 80
<cool_capricorn80 () hotmail com> wrote:
              


                       Hi!
                      

                        (Sorry for repeating my question)

                       I am looking to calculate the end-to-end delay
between two soft phone/hard phone. I have asterisk server and configured
ntp server on the same machine and synchronized it with ntp pool.
                       
                       I have seen that Wireshark can be used to check
the jitter. But I am not sure how can i calculate the end to end. 

                      May be this is not related to the mailing list
topic but please help me if anyone has some information.

                      Regards,


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