[asterisk-bugs] [JIRA] (ASTERISK-26487) RTP stream frozen when receiving RTCP packets

[Daniel Berteaud (JIRA)]

Daniel Berteaud created ASTERISK-26487:
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             Summary: RTP stream frozen when receiving RTCP packets
                 Key: ASTERISK-26487
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-26487
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
    Affects Versions: 13.11.2, 13.11.1
         Environment: CentOS 7 x86_64
            Reporter: Daniel Berteaud


Using asterisk rpm from Tucny (https://ast.tucny.com/) on CentOS 7 x86_64, with FreePBX 13 (from sources). Phones are Polycom soundpoint IP331 and IP651. A patton smartnode SN4636 is used to connect 2 T0 lines.

Everything is working well, except that sometime, very randomly, we have no more sound, for exactly 4 seconds. This is occuring very randomly (can be anywhere from every 5 minutes, to no problem in two hours of call). This coupled with the very short duration of the problem make it quite hard to analyse.

After spending hours looking at this, I found that the problem always occures when asterisk receive an RTCP packets (from either one of the polycom, or the smartnode). When the problem occurs, asterisk stops sending RTP streams for this call for exactely 4 sec (we can see this with a tcpdump capture on the asterisk server).

When the error occurs, there's nothing particular in asterisk log, no matter the log level. It looks like a thread is blocked. Not sure where, but maybe the duration of 4 seconds can talk to someone ?

I've worked around the problem by simply droping RTCP packets with this iptables rule:

-A INPUT -p udp --dport 10000:20000 -m length --length 90:130 -j DROP

Since then, no more audio issue.



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