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The leap second is coming by Tomonori TAKADA [APRICOT 2015]

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A presentation given at the Lightning Talks session of APRICOT 2015 on Thursday, 5th March 2015.

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The leap second is coming by Tomonori TAKADA [APRICOT 2015]

  1. 1. The leap second is coming. Kyusyu Telecommunication Network Co.,Inc. (QTNet) Tomonori TAKADA
  2. 2. 1Kyushu Telecommunication Network Co., Inc. Agenda • A leap second will be inserted in this year. • How to adjust NTP for the leap second • The insertion of the previous leap second (2012) • QTNet NTP servers overview. • QTNet Plan for The leap second of 2012 • QTNet Plan for The leap second of 2015
  3. 3. 2Kyushu Telecommunication Network Co., Inc. A leap second will be inserted this year July 1, 2015 +0900 (JST) 23:59:58 23:59:59 23:59:60 00:00:00 00:00:01 June 30, 2015 (UTC) 08:59:58 08:59:59 08:59:60 09:00:00 09:00:01
  4. 4. 3Kyushu Telecommunication Network Co., Inc. How to adjust NTP for the leap second a description of the NTP/SNTP Version 4 message format Value and meaning of the Leap Indicator ※ adapted from http://www.rfc-base.org/txt/rfc-2030.txt • Leap Indicator(LI) is used to adjust for the leap second. • The node which is received as “LI=01”, adjusts the host clock by itself using OS/Kernel functionality when inserting the leap second. • LI just indicates that leap second will be happen.
  5. 5. 4Kyushu Telecommunication Network Co., Inc. The insertion of the previous leap second (2012) • The previous leap second was inserted on July 1, 2012 at +0900(JST). • Several problems were reported, especially on Linux. 1. OS rebooted after it received the leap indicator. 2. CPU usage reached 100% on multiple hosts running some specific applications after the leap second was inserted.
  6. 6. 5Kyushu Telecommunication Network Co., Inc. QTNet NTP Servers overview GPS time server JJY (Dial-up) time server via PSTN Stratum1 Stratum2 peer peer ntp server 1 ntp server 2 ntp server 3 QTNet Servers internet ※NICT is an organization that determines and maintains Japan Standard Time or JST, and distributes JST in various ways.
  7. 7. 6Kyushu Telecommunication Network Co., Inc. QTNet Plan for the leap second of 2012 • We did not use the Leap Indicator. • We had gotten information of old OS/Kernel bugs which were relevant to the leap indicator. • Our Stratum1 servers could adjust for a leap second without using the leap indicator, “Gradually adjust mode”. About two hours before the leap second, Our Stratum1 servers began to set the clock back slowly.
  8. 8. 7Kyushu Telecommunication Network Co., Inc. QTNet Plan for the leap second of 2012 via PSTN Stratum1 Stratum2 peer peer ntp server 1 ntp server 2 ntp server 3 QTNet Servers GPS time server JJY (Dial-up) time server excluded from synchronizing Leap indicator distributionGradually adjust mode Gradually adjust mode
  9. 9. 8Kyushu Telecommunication Network Co., Inc. Status at the leap second insertion on 2012 via PSTN Stratum1 Stratum2 peer peer ntp server 1 ntp server 2 ntp server 3 QTNet Servers GPS time server JJY (Dial-up) time server Gradually adjust mode Gradually adjust mode ○ ○ ○ × ×
  10. 10. 9Kyushu Telecommunication Network Co., Inc. The reasons for the peer status failure via PSTN Stratum1 Stratum2 ntp server 1 ntp server 3 ntp server 2 GPS time server JJY (Dial-up) time server Start time for setting the clock back 1/64sec 1/128sec 1/128secPolling interval 125 minutes before 120 minutes before
  11. 11. 10Kyushu Telecommunication Network Co., Inc. Possible plans for The leap second of 2015 • Plan A: Using the Leap Indicator • We have to update our server’s OS/Kernel. • Plan B: Not using the Leap Indicator (Using “Gradually adjust mode” ) • Single Time source (Stratum1). • We make the Stratum2 polling interval to Stratum1 shorter than before (about each 16 seconds).
  12. 12. 11Kyushu Telecommunication Network Co., Inc. The leap second is Coming. July 1, 2015 +0900 (JST) 23:59:58 23:59:59 23:59:60 00:00:00 00:00:01 June 30, 2015 (UTC) 08:59:58 08:59:59 08:59:60 09:00:00 09:00:01
  13. 13. 12Kyushu Telecommunication Network Co., Inc. Let's do our best.
  14. 14. 13Kyushu Telecommunication Network Co., Inc. Appendix Sites in JPN http://ringeye.jawfish.org/~ori/misc/leapsecond-20120701.html http://chicchaki.cocolog-nifty.com/kanetamas_memo/2005/11/ntp_2b1d.html http://www.rfc-base.org/txt/rfc-2030.txt https://www.seiko-sol.co.jp/support/download/LeapSecond20120701_2520_30_40.pdf http://www-06.ibm.com/jp/linux/tech/doc/0019db89.html Sites in English http://jjy.nict.go.jp/time/teljjy/teljjy_p1-e.html http://googleblog.blogspot.jp/2011/09/time-technology-and-leaping-seconds.html

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