[asterisk-bugs] [Asterisk 0016936]: Qualify frequency has big pauses. Asterisk stops sending SIP OPTIONS to keep NAT alive

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
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https://issues.asterisk.org/view.php?id=16936 
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Reported By:                ib2
Assigned To:                
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Project:                    Asterisk
Issue ID:                   16936
Category:                   Channels/chan_sip/General
Reproducibility:            sometimes
Severity:                   major
Priority:                   normal
Status:                     feedback
Asterisk Version:           1.6.2.4 
JIRA:                       SWP-993 
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-03-01 13:54 CST
Last Modified:              2010-04-19 22:59 CDT
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Summary:                    Qualify frequency has big pauses. Asterisk stops
sending SIP OPTIONS to keep NAT alive
Description: 
We have several SIP phone peers that that becomes UNREACHABLE since
upgrading to Asterisk 1.6.2.x

[10:08:44] chan_sip.c: Peer '202_117' is now UNREACHABLE!  Last qualify:
100
[10:11:25] chan_sip.c: Peer '202_117' is now Reachable. (86ms / 2000ms)
[11:59:03] chan_sip.c: Peer '202_117' is now UNREACHABLE!  Last qualify:
91
[12:11:27] chan_sip.c: Peer '202_117' is now Reachable. (85ms / 2000ms)
[13:17:21] chan_sip.c: Peer '202_117' is now UNREACHABLE!  Last qualify:
90
[13:41:27] chan_sip.c: Peer '202_117' is now Reachable. (92ms / 2000ms)

The phone is UNREACHABLE until it registers again. The phone does not know
that it is UNREACHABLE.
Asterisk reports the phone as UNREACHABLE after a big pause in sending SIP
OPTIONS to keep NAT alive. Therefore NAT table is lost and asterisk cannot
receive SIP OK reply from the phone.

The typical interval between the occurrence is shown above
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 (0120623) xiaoyem (reporter) - 2010-04-19 22:59
 https://issues.asterisk.org/view.php?id=16936#c120623 
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I experienced this problem when I using 1.6.2.7-rc1 under Xen.  I enabled
the devel mode (--enable-dev-mode), selected the DEBUG_SCHEDULER and
DUMP_SCHEDULER flags.  It turns out that the time in Xen is a little
faster, in my case, about 100 secs per hour.  I have a crontab script that
synchronizes time every hour.  After synchronization, the time in Xen is
turned back 100 secs, thus long pause occurs. 

Issue History 
Date Modified    Username       Field                    Change               
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2010-04-19 22:59 xiaoyem        Note Added: 0120623                          
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