[asterisk-dev] Question regarding RTCP - NACK

Joshua C. Colp jcolp at digium.com
Mon Feb 11 04:44:35 CST 2019


On Mon, Feb 11, 2019, at 5:16 AM, Floimair Florian wrote:
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> We recently ran into something regarding RTCP – Generic NACK Feedback,
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> which was introduced with https://issues.asterisk.org/jira/browse/ASTERISK-27810
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> Me and my colleague read through RFC 4585 Section 6.2.1 “Generic NACK” 
> but we didn’t really find an answer to our question,
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> which is the following:
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> Asterisk sends Receiver Reports on the RTCP port (RTP+1), whereas
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> the NACK is sent on the RTP port which confuses the other end of our 
> system (rtpengine).
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> Is Generic NACK supposed to be sent to the RTP port or isn’t it 
> supposed to be sent on the RTCP port (which would make this a bug in 
> the current implementation)?

It's supposed to be sent on the RTCP port, but it was developed for the browser where bundle would have it all on the same port so it's likely the case was not specifically tested in a non-bundle environment.

-- 
Joshua C. Colp
Digium - A Sangoma Company | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org



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