[asterisk-bugs] [JIRA] (ASTERISK-26766) Asterisk 13 IAX2 jitterbuffer causes packet loss

[Kirsty Tyerman (JIRA)]

Kirsty Tyerman created ASTERISK-26766:
-----------------------------------------

             Summary: Asterisk 13 IAX2 jitterbuffer causes packet loss
                 Key: ASTERISK-26766
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-26766
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Channels/chan_iax2
    Affects Versions: 13.9.1
         Environment: Fedora 25, Fedora 24
            Reporter: Kirsty Tyerman
         Attachments: 2017-02-03-11-06-04_5013-5003_eng_mf1.wav

We have two quad core i7 Asterisk boxes running Fedora 24 or Fedora 25 using the vanilla Fedora compiled Asterisk 13.9.1

Between the two machines is an IAX2 trunk which is passing a small amount of SIP traffic (less than 10 calls).

When the jitterbuffer is enabled in IAX2, it causes what could be described as packet loss - the noticable result is choppy audio being heard on all phone calls.

This is not an intermittent problem - it happens to every single call that traverses the link. There are no networking switches / routers between the two machines and we have confirmed it is not a networking issue.

The issue occurs with G729 or ulaw and IAX is trunking multiple SIP calls.

There is no other processes running on the servers other than Asterisk and they are not showing any CPU loading issues.

The behavior is resolved as soon as the IAX2 jitterbuffer is turned off in iax.conf (jitterbuffer=no).

We have subsequently reverted both machines to Asterisk 11.13.1 and the bug is not present, so we believe it is a bug that has been introduced to the 13 branch.

The following iax2 show netstats shows significant Lost %:

calhost*CLI> iax2 show netstats
                           -------- LOCAL ---------------------  -------- REMOTE --------------------
                           Channel               RTT  Jit  Del  Lost   %  Drop  OOO  Kpkts  Jit  Del  Lost   %  Drop  OOO  Kpkts FirstMsg    LastMsg
                           IAX2/192.168.122.132:4569    3  150  204   366  32     0  530      0    1   60    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    1  150  190   433  33     0  630      0    1   41    10   1     0    0      0 Rx:NEW      Rx:ACK
                           IAX2/192.168.122.132:4569    3  150  191   340  28     0  547      0    1   60    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    3  150  191   430  33     0  629      0    1   41    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    3  150  190   406  32     0  581      0    1   41    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    3  150  190   308  25     0  534      0    1   60    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    3  151  211   348  29     0  549      0    1   41    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    3  150  210   401  32     0  582      0    1   61    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    1  150  190   373  32     0  531      0    1   41    10   1     0    0      0 Rx:NEW      Tx:ACK
                           IAX2/192.168.122.132:4569    3  150  190   438  33     0  628      0    1   41    10   1     0    0      0 Rx:NEW      Tx:ACK
                           10 active IAX channels



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