Wireshark-users: Re: [Wireshark-users] about the VOIP bandwidth

From: Jaap Keuter <jaap.keuter@xxxxxxxxx>
Date: Sun, 30 Jan 2011 23:44:36 +0100

On Sun, 30 Jan 2011 22:21:56 +0100, Anders Broman wrote:

nangergong skrev 2011-01-30 20:12:
Hi, all:

  I'm using wireshark to capture VOIP streams, the Codec used in the VOIP session is G711, which uses bandwidth of 64kbps.

  When I follow the following steps to analyse the VOIP streams:

  Telephony->RTP->show all streams->Analyze,

  I found that the IP BW (bandwidth) column shows that the bandwidth is about 81.6 kbps.   I also used a traffic monitoring program to monitor the traffic, which shows the bandwidth used is about 64kbps (conformant to G711 bit rate ). So, I wonder whether wireshark is accurate in measuring the bandwidth? or even other metrics such as jitter,etc..

  Thank you!

The codec data inside the RTP is 64Kbit/s with RTP/UDP/IP/Ethernet headers the rate should be something like 96Kb/s, if memory serves.
/Anders

It all depends on the protocol layer you look at. This site lets you have a good insight in what's involved here.

Thanks,
Jaap