G450: Why does Avaya G450 gateway sends several (9) RTCP Sender Report packets within 1 sec at the start of a new RTP session?

Doc ID		SOLN315513
Version:		1.0
Status:		Published
Published date:		19 Sep 2017

Author:

Levente Szabo

Details

G450: Avaya VoIP G450 MP160 v137

Problem Clarification

At the start of a new RTP Session between G450 Gateway and IP-Phone/other Endpoint, the G450 Gateway generates many (9) RTCP Packets in ~500 milliseconds. However, on "system-parameters ip-options" form the RTCP report period is set to 5 seconds: "RTCP Report Period(secs): 5".

After the RTP session established, the configured 5 second intervall is kept, but at the start of a new RTP session 9 RTCP packets are sent by the G450. Why does G450 do that?

Cause

Customer needs clarification about why G450 Gateway generates many (9) RTCP Packets in ~500 milliseconds at the start of a new RTP Session.

Solution

The nine RTCP packets sent at the start of the call is the Early RTCP mode as per RFC 4585.
https://tools.ietf.org/html/rfc4585

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