Interpreting ITU

The ITU has produced over a dozen standards to do with time and synchronization over the last ten years. Why so many? Partly it’s a matter of evolution, and partly it’s a matter of purpose. The first standard released back in 2006 was G.8261, and it covered “general aspects” of frequency distribution in packet networks.Time wasn’t a topic back then. G.8261 evolved into a set of standards for frequency distribution:

  • G.8261.1 – network performance standards
  • G.8262 – Synchronous Ethernet clock performance
  • G.8265 – packet network architecture for frequency distribution
  • G.8265.1 – profile for frequency distribution using PTP

When the committee started to look at time synchronization in 2010, a parallel set of standards was developed covering similar topics. These were given the numbers G.827x, and so far the following recommendations have been published:

  • G.8271 – general aspects
  • G.8271.1 – network performance standards
  • G.8272 – Primary Reference Time Clock
  • G.8273 – packet clock types
  • G.8273.2 – Boundary Clock performance
  • G.8275 – packet network architecture for time distribution
  • G.8275.1 – profile for time distribution using PTPG.8273 – packet clock types

Tim Frost
Strategic Technology Manager, Calnex Solutions.


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