Wireshark-users: Re: [Wireshark-users] Help. I do not know much about anything.... I amtrying to
From: Andreas Fink <[email protected]>
Date: Fri, 9 Feb 2007 22:08:54 +0100
I think his problem is more on the radio link level than on the codec level.
Using G.711 would be 80kbps worth of data and very timing sensitive usually.
Most modern IP phones use G.729. Now if the other side recodes the voice in something like G.728 then you have a serious quality issue due to double compression.

On 09.02.2007, at 21:48, Chet Seligman wrote:

Hopefully your folks use the G.711 codec. If so you can do a capture and save forward and reverse streams as a .au file. This will play with Windows Media and you will hear what they are hearing. Else the following still applies:

  1. WS will make delay and jitter graphics
  2. Filter the capture for RTP and save the filtered version.
    1. Export to CSV and read with Excel
    2. Determine the standard deviation of the delta time between packets column
    3. Make a frequency table of the delta t
    4. 4 x stdev = 99.97% of a normal distribution. If 4x stdev is less than 20ms then you are loosing very few packets and have micro-jitter. Else, the reverse.
  3. If you meet the standard deviation test then the network is doing a good job and the ip-phones are not. Often phone firmware or lousy wires are responsible. More than 50% of ip-phone problems are speed/duplex mismatches at the network jack.


From: [email protected] [mailto:[email protected]] On Behalf Of Chuck Botwin
Sent: Friday, February 09, 2007 11:29 AM
To: [email protected]
Subject: [Wireshark-users] Help. I do not know much about anything.... I amtrying to see if a wireless connection between 2


Help.  I do not know much about anything....  I am trying to see if a wireless connection between 2 buildings is adequate.  I have played wire Wireshark and see that if I use my IP address as the interface, and a computer's IP address somewhere else locally, I can see packets sent and received, with no dropped packets.  I plan to go to a friends site to do this exercise between 2 buildings.  This in itself is not a big deal, but I want to get an idea of the available bandwidth between the buildings.  Their problem is that their IP phones have very poor quality.  The people who installed their antennas say it is the IP phone system.  The antenna people report 8 megabit thru-put.  The IP phone vendors say it is the wireless connection.  I want to get to the bottom of this.  Any suggestions? How can I measure bandwidth? If there are no dropped packets between the buildings should I assume the problem lies with the IP phones??
Thanks in advance.
Chuck Botwin
Botwin Communications
Office: (770) 218-0008 xt 222
Fax: (770) 218-9291
Cell: (770) 856-6690
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