From 77ac34c066f3d0e70a59814a9bc88fc5243846e3 Mon Sep 17 00:00:00 2001 From: kpfleming Date: Fri, 22 Apr 2005 04:39:41 +0000 Subject: [PATCH] more clarification of time changes and how they affect Asterisk (bug #4020) git-svn-id: http://svn.digium.com/svn/asterisk/trunk@5497 f38db490-d61c-443f-a65b-d21fe96a405b --- README | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/README b/README index 71925de70..3378101d3 100755 --- a/README +++ b/README @@ -164,20 +164,27 @@ from the variables specified above. * SPECIAL NOTE ON TIME - Those using SIP phones should be aware the Asterisk is sensitive to large -jumps in time. Those who live in areas that are on Daylight Savings Time (or -equivalent) should set their system and hardware clocks to use UTC in order -to avoid any possible jumps in system time. There should be no noticeable -effects to the user, as you should still set your system to use the local -offset from UTC. + Those using SIP phones should be aware the Asterisk is sensitive to +large jumps in time. Manually changing the system time using date(1) +(or other similar commands) may cause SIP registrations and other +internal processes to fail. If your system cannot keep accurate time +by itself use NTP (http://www.ntp.org/) to keep the system clock +synchronized to "real time". NTP is designed to keep the system clock +synchronized by speeding up or slowing down the system clock until it +is synchronized to "real time" rather than by jumping the time and +causing discontinuities. Most Linux distributions include precompiled +versions of NTP. Beware of some time synchronization methods that get +the correct real time periodically and then manually set the system +clock. - Even for those who don't live in DST zones, this issue may manifest itself -if the administrator makes large manual time adjustments. Thus, it is good -practice to keep the time on your Asterisk server synced to a reliable -source, such as an NTP server. + Apparent time changes due to daylight savings time are just that, +apparent. The use of daylight savings time in a Linux system is +purely a user interface issue and does not affect the operation of the +Linux kernel or Asterisk. The system clock on Linux kernels operates +on UTC. UTC does not use daylight savings time. - Also note that this issue is separate from the clocking of TDM channels, and -is known to at least affect SIP registrations. + Also note that this issue is separate from the clocking of TDM +channels, and is known to at least affect SIP registrations. * MORE INFORMATION