Ethereal-users: Re: [Ethereal-users] RTP packets not captured..

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From: Shreesha Kunjibettu <kshreesha@xxxxxxxxx>
Date: Mon, 2 Feb 2004 13:52:49 -0800 (PST)
Thanks for the info. I moved all my connections to a
ethernet hub and I did have similar results. I know I
am capturing the correct IP @ and port # ( I do this
based on SDP traces). I also tried capturing directly
on the SIP phone also using ethereal. Same results. 
However after doing few more experiments - it looks
like I am able to capture first 4 packets (G.711 or
G.729), but after that I do not see any RTP packets.
If I make another call immediately, I do not see RTP
information. If I wait for a while (for eaxmple after
60 minutes etc..) and call back again, I see 4 more
RTP packets. I know it does not sound rational, but
that's what I am seeing.
--- Martin Regner <martin.regner@xxxxxxxxx> wrote:
> 
> Shreesha Kunjibettu wrote:
> 
> > However I did not see any UDP packets (except
> > those that are decoded as SIP signaling packets).
> 
> The RTP packets normally goes directly between
> endpoints, e.g. directly
> between client(s) and/or gateway(s), i.e. normally
> not the same was the SIP
> signalling.
> So you should maybe should try to capture the
> packets by mirroring the
> ip-switch port for client or gateway (or use a hub
> where gateway/client is
> located) if you are currently trying to capture them
> in the SIP-proxy.
> The SDP signalling will give information about what
> port-numbers/ip-addresses are used for the RTP
> packets and could be useful
> when trying
> to capture those packets.
> If you are using a capture filter you may need to
> modify it to capture
> packets between other ip-addresses that the
> SIP-signalling.
> 
> 
> 
> 
> 
> 
> 
> 
> 



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