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@ -164,20 +164,27 @@ from the variables specified above.
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* SPECIAL NOTE ON TIME
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Those using SIP phones should be aware the Asterisk is sensitive to large
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jumps in time. Those who live in areas that are on Daylight Savings Time (or
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equivalent) should set their system and hardware clocks to use UTC in order
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to avoid any possible jumps in system time. There should be no noticeable
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effects to the user, as you should still set your system to use the local
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offset from UTC.
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Even for those who don't live in DST zones, this issue may manifest itself
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if the administrator makes large manual time adjustments. Thus, it is good
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practice to keep the time on your Asterisk server synced to a reliable
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source, such as an NTP server.
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Also note that this issue is separate from the clocking of TDM channels, and
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is known to at least affect SIP registrations.
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Those using SIP phones should be aware the Asterisk is sensitive to
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large jumps in time. Manually changing the system time using date(1)
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(or other similar commands) may cause SIP registrations and other
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internal processes to fail. If your system cannot keep accurate time
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by itself use NTP (http://www.ntp.org/) to keep the system clock
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synchronized to "real time". NTP is designed to keep the system clock
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synchronized by speeding up or slowing down the system clock until it
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is synchronized to "real time" rather than by jumping the time and
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causing discontinuities. Most Linux distributions include precompiled
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versions of NTP. Beware of some time synchronization methods that get
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the correct real time periodically and then manually set the system
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clock.
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Apparent time changes due to daylight savings time are just that,
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apparent. The use of daylight savings time in a Linux system is
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purely a user interface issue and does not affect the operation of the
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Linux kernel or Asterisk. The system clock on Linux kernels operates
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on UTC. UTC does not use daylight savings time.
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Also note that this issue is separate from the clocking of TDM
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channels, and is known to at least affect SIP registrations.
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* MORE INFORMATION
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Kevin P. Fleming
22 years ago