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In this episode Brady Volpe of Nimble This and The Volpe Firm, discusses PTP clocks with subject matter experts Jim Olsen from Microchip and Rob Jodrie from Syncworks. This discussion includes a very high level break down of PTP profiles and why you should care? The evolution of PTP, Boundary clocks, best practices and things to look out for. You may think this is not a big topic but this is something that impacts all operators big, medium or small when deploying distributed access architecture (DAA) such as R-PHY nodes, 5G technology and other related technologies requiring precise timing.

The discussion is on all things DOCSIS. Tips, suggestions and recommendations. Another power hour of cable.

PTP Clocks:

  1. Intro
  2. Why do we need PTP? – High accuracy needed for R-PHY
  3. What is PTP? – The Precision Time Protocol (PTP) is a protocol used to synchronize clocks throughout a computer network. On a local area network, it achieves clock accuracy in the sub-microsecond range, making it suitable for measurement and control systems.
  4. What does it do in our network?
  5. NTP – is a best effort and PTP – is engineered and guaranteed
    1. The older and more well-known protocol is the Network Time Protocol (NTP). The newer protocol is the Precision Time Protocol (PTP).
  6. Modulation on CMTSs mCMTS
  7. What happens when we lose PTP timing into the CMTS? Master clocks connected to a GPS. GPS is used for traceability
  8. CableLabs found PTP technology for CMTSs accuracy, especially needed for DAA and RPD applications
  9. Redundancy very important for reliability and to prevent outages
  10. What happens when you disconnect the PTP timer from a CMTS?
    1. Modems will go offline even quickly will cause outages
    2. Two grandmasters ideal
    3. Best upfront network design important
    4. No hold over from PTP Clocks to CMTS
  11. Next steps in PTP timers
    1. 5G – Boundary clock function – full on path support for PTP extension of PTP version 2
    2. Network asymmetry
    3. Grandmaster function and client
    4. Asymmetry – the typical scenario
    5. Different classes of Boundary clocks
  12. CCAP can support both traditional and RPDs, what do PTP timers do in integration?
    1. Flexible mac architecture
    2. Remote Mac-PHY
    3. Video remote mac-phy
      1. video sync mode
      2. video asynchronous mode
    4. What do you do if adding 5G?
  13. Do we need PTP on the Remote Mac PHY
  14. PTP timing at the Mac-PHY needed?
  15. Remote MAC-PHY doesn’t need PTP but…
  16. Looking to the future GPS needed
  17. PTP services out of a CMTS
    1. Mobility Services
    2. Fixed wireless
    3. Low latency
  18. Sync evolution / GNS Vulnerability / Jamming
    1. Best practices
  19. Starlink? Could it replace GPS?
    1. GPS paid for by tax payers
    2. LEO – questionable
    3. Alternative to GPS? Satellite services get timing from GPS
    4. Satellite service are subscription
    5. Cesium clock
    6. Shows how important clocks are in the network
    7. Antenna alarm
  20. Any other things we should look out for?
    1. Design considerations
    2. Cable delay setting from antenna from receiver, cable type, how far away the antenna is from receiver
  21. Synchronous Ethernet and boundary clock functions go hand in hand
    1. 5G friend or Foe at SCTE EXPO 2021
  22. Thanks to the Chat room!

End Podcast

Thank you for your time today. This was a great episode.  Our next Episode 79 in November

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