Clocking and sync
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The document discusses various time synchronization protocols and concepts, including synchronous Ethernet (SyncE), Precision Time Protocol (PTP), and Network Time Protocol (NTP). It categorizes time servers into different strata, explaining their roles and synchronization methods within network systems. Additionally, the document outlines relevant standards and specifications for achieving accurate time distribution in packet networks.
![Stratum
Stratum 0
These are high-precision timekeeping devices such as atomic (cesium, rubidium)
clocks, GPS clocks or other radio clocks. They generate a very accurate pulse per
second signal that triggers an interrupt and timestamp on a connected computer.
Stratum 0 devices are also known as reference clocks.
Stratum 1
These are computers whose system clocks are synchronized to within a few
microseconds of their attached stratum 0 devices. Stratum 1 servers may peer with
other stratum 1 servers for sanity checking and backup.[8] They are also referred to as
primary time servers.[2][3]
Stratum 2
These are computers that are synchronized over a
network to stratum 1 servers. Often a stratum 2 computer will query several stratum 1
servers. Stratum 2 computers may also peer with other stratum 2 computers to
provide more stable and robust time for all devices in the peer group.
Stratum 3
These are computers that are synchronized to stratum 2 servers. They employ exactly
the same algorithms for peering and data sampling as stratum 2, and can themselves
act as servers for stratum 4 computers, and so on.](https://image.slidesharecdn.com/clockingandsync-150211025910-conversion-gate01/85/Clocking-and-sync-3-320.jpg)
Clocking and sync
- 1. Clocking & Sync SyncE , NTP , PTP etc. Oded Rotter oded1233@gmail.com Based On: http://en.wikipedia.org/wiki/Synchronous_Ethernet http://www.metroethernetforum.org/Assets/White_Papers/Packet_Synchronization_over_Carrier_Ethernet_Net works_for_MBH_2012021.pdf http://www.ipinfusion.com/products/zebos/protocols/carrier-ethernet/timing-and-synchronization http://www.cisco.com/c/en/us/products/collateral/routers/asr-9000-series-aggregation-services- routers/white_paper_c11-500360.html http://en.wikipedia.org/wiki/Network_Time_Protocol http://en.wikipedia.org/wiki/Precision_Time_Protocol http://en.wikipedia.org/wiki/Synchronization_in_telecommunications http://tagus.inesc-id.pt/~pestrela/timip/Challenges_deploying_PTPv2_in_a_Global_Financial_company.pdf www.ietf.org/proceedings/68/slides/tictoc-3/tictoc-3.ppt http://www.nist.gov/el/isd/ieee/upload/tutorial-basic.pdf www.eecis.udel.edu/~mills/database/brief/distlec/distlec.ppt
- 2. מושגים • Synchronous Ethernet (SyncE) • Precision Time Protocol (PTP) • Network Time Protocol (NTP) • Simple Network Time Protocol (SNTP) • Adaptive Clock Recovery (ACR) • Primary Reference Clock (PRC) • Primary reference source (PRS) • Cesium oscillator • Global Positioning System (GPS) • Building Integrated Timing Supply (BITS) • Synchronization Supply Unit (SSU) • Two-Way Time Transfer (TWTT)
- 3. Stratum Stratum 0 These are high-precision timekeeping devices such as atomic (cesium, rubidium) clocks, GPS clocks or other radio clocks. They generate a very accurate pulse per second signal that triggers an interrupt and timestamp on a connected computer. Stratum 0 devices are also known as reference clocks. Stratum 1 These are computers whose system clocks are synchronized to within a few microseconds of their attached stratum 0 devices. Stratum 1 servers may peer with other stratum 1 servers for sanity checking and backup.[8] They are also referred to as primary time servers.[2][3] Stratum 2 These are computers that are synchronized over a network to stratum 1 servers. Often a stratum 2 computer will query several stratum 1 servers. Stratum 2 computers may also peer with other stratum 2 computers to provide more stable and robust time for all devices in the peer group. Stratum 3 These are computers that are synchronized to stratum 2 servers. They employ exactly the same algorithms for peering and data sampling as stratum 2, and can themselves act as servers for stratum 4 computers, and so on.
- 4. זה מה? •השתמשנו בעבר(שירות ספקי)באמצעות שעונים וסנכרון בהפצת ה ברשת מובנים מנגנונים-TDM(SDH,PDH,T1,E1) •ל במעבר עכשיו-IP,אחר פתרון להיות צריך. •היבטים כמה: וסנכרון שעון הפצת •SyncE-ברמה תדר הפצת מאפשרהפיזיתממשק גבי עלאתרנט. פרמטרים אותם את לספק אמור(Jitter,Wander Tolerance, וכו תדרים')ברשתות כמוSDHהבאים התקנים על המתבססות: TU-T G.813 and G.812 or Telcordia GR-1244-CORE ITU-T G.707, G.781, Telcordia GR-253-CORE, ANSI T1.101.
- 5. זה מה?(המשך) •ברמת שעון פתרונותL2,L3: –NTP(ובעיותיו גרסאותיו שלל על והידוע המוכר) –PTP(יותרמ מדויק-NTP+תדר העברת) –Circuit Emulation Services (CES) encapsulation (לזקניםגיקיםבלבד)
- 9. SyncE–רלוונטיים תקנים • ITU-T G.8261: Timing and synchronization aspects in packet network • ITU-T G.8262: Timing characteristics of Synchronous Ethernet equipment slave clock • ITU-T G.8264: Distribution of timing through packet networks • ITU-T G.781: Synchronization layer functions
- 10. SyncE
- 11. SyncE TLV
- 14. NTP 1985 NTPv0 (RFC 958) NTP Packet Header, offset & delay calculation 1988 NTPv1 (RFC 1059) Comprehensive specification of protocol and algorithms Client and server, symmetric operational modes 1989 NTPv2 (RFC 1119) NTP Control Message Protocol (Management of clients) Support for cryptographic authentication based on 64-bit data encryption Standard (DES) keys 1992 NTPv3 (RFC1305) Improve stability and accuracy (new algorithm) Broadcast operational mode 2010 NTPv4 RFC5905 Support of security features Support of automatic configuration Algorithm improvements (Performance) Backward compatible with NTPv3 Significant revision of NTPv3
- 15. SNTP (RFC2030) •מ יותר פשוט ישום-NTP •מ מדויק פחות-NTP
- 16. PPTP PPTP (RFC2637, ieee1588), PPTPv2 •יחסיClient /Server(היררכי)שיהוי ומדידת שעון בהפצתבינהם •מדידתלינק ברמת שיהוי(PPTPv2) •בחירתBest Master
- 18. PPTP
- 22. ב תוספות-PTPv2 •מננו קטן דיוקשניה •יותר מהירות ותשדורות דגימה קצבי •ב גם תמיכה-Unicast •באסימטריות תמיכה •שרידות שיפור •להגדרה הניתנת היררכיה •UDP •Transparent clocks
- 23. טוב זה מה בשביל? •ברירה אין 27
- 24. השטן של פרקליטו שואל מה? •פה חדש מה? •עודBuzzword? •ליהודים טוב זה? •לזכור שצריך תיבות ראשי עוד? •עודשצריך תקניםללמוד? 27
- 25. של לשאלותיו וארוכה מנומקת תשובה השטן של פרקליטו? 27
- 26. סרט לראות לי בא... • https://www.youtube.com/watch?v=QkEmJrLXHUk • https://www.youtube.com/watch?v=N7nTCHxBitU • https://www.youtube.com/watch?v=250reOmrN70 • https://www.youtube.com/watch?v=eitxR-_lMxs • https://www.youtube.com/watch?v=yw-gd01aOYg • https://www.youtube.com/watch?v=9Efij8zW8-k