On 11/14/06, Razor Ramone <[EMAIL PROTECTED]> wrote:
> Hello,
>
> for my school project, I decided to analyze a VoIP call using wireshark but
> there are some things that are not clear to me.
> below, I am always talking about RTP packets
>
> first of all, in a conversation, I expect that the initiator and the
> receiver take turns talking. Therefore, I expected to see that when the
> initiator is sending packets (talking), the receiver is listening (not
> sending packets), but that is not the case in my Wireshark captures.
> What I see is that the receiver generally sends packets continuously at a
> frequency of 1 packet every 20ms.
>
> On the other hand, the receiver is simultaneously sending packets in a
> different pattern. The receiver sends 4 to 5 packets almost at instantly (
> 0.0x ms between each packet), then it waits 80 to 100ms during which it
> receives 4 to 5 packets from the initiator, then it sends another burst of
> 4-5 packets.
>
> So my questions so far are
> -Why do initiator and receiver send packets simultaneously?
may full-duplex be the answer?

> -Why do initiator send packets in different patterns? (20ms vs a burst of
> packets followed by a wait)
Buffering problems, network congestion, transport problems, etc...
that should be seen on case per case basis.

>
> The answer to my first question, I suspect, would be noise, or synhetic
> noise was introduced into the conversation on purpose (comfort noise) but I
> am not sure about this.
That can be.
>
> My final question is:
> -If it is true that the reasons initiator and receiver send packets at the
> same time, why, then, are there times that they do not send packets at the
> same time? (in one conversation, the initiator is talking for an extensive
> period of time during which the receiver sends no packets)
may silence-suppression be the answer?

>
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>


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