Hi John, So what happens when g729 is used with VAD and the far end media gw interrupts sending rtp packets on silence detection ? Or am i missing something ? --- Cumprimentos / Best regards Marco Teixeira email/gtalk/msn: admin at marcoteixeira.com skype: admin-marcoteixeira.com --- Did you know that Marco Teixeira is an independent, senior, industry expert, consultant ? Is expertise is available for hire. --- On Thu, Sep 13, 2012 at 4:57 PM, John S. Robinson <jsr at communichanic.com>wrote:
Clint -- The answer to this is fairly straightforward. * **If* your Empirix Hammer is providing media quality monitoring, it *must*rely on the the actual RTP media stream that it is monitoring.
A media stream is defined as Source IP:Port plus Destination IP:port plus *SSRC. *SSRC is often over overlooked, but strict media gateways or media relays *may* refuse to process any further RTP packets when SSRC or Source IP:port changes without any new SDP offer-answer.
RTP Start is established when the the *first *packet is received on the * Destination* IP:port negotiated by SDP offer:answer. At that time the RTP monitor (or any strict media handler) *learns* the *Source* IP:Port, and the SSRC
As someone else has pointed out, there is no "RTP end" packet. So "RTP end" is declared when there are no further media packets received on the established stream, defined by Source IP:Port plus Destination IP:port *plus* *SSRC*. This may happen at any time in an established session. If something "goes wrong" in a media stream, the "RTP end" *may *be declared well before any sip method (usually BYE) which ends the session. This explains why you "have seen this many times preceeding a BYE - or even without a BYE." Any "RTP end" which occurs substantially before a BYE *without* an almost immediate new "RTP Start" indicates the potential media failure. If that happens, the media failure may be the root cause of the BYE. In that case, you may be loosing revenue.
None of this is in any way related to presence or absence of RTCP.
Hope this helps. If you would like any further discussion, please contact me privately.
Best regards,
Communichanic Consultants, Inc John S. Robinson <jsr at communichanic.com>, President
On 9/12/2012 17:25, Clint Mojzes wrote:
We are using a tool called Empirix Hammer to analyze and report on our network traffic. This tool as uncovered something that it calls ?RTP End? and I?m trying to get a better definition of what it means. I haven?t been able to find anything online, including RFCs etc. Basically when the Hammer see this special packet, it is when a phone or media gateway is tearing down a call. Logically speaking it is identifying the end of a media stream, but I?m looking for a technical definition. Can anyone provide any insight?****
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Thanks,****
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-Clint****
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