ITU-T G.8275.2 PDF

This Recommendation specifies a profile for telecommunication applications based on [IEEE 1588] precision time protocol (PTP). The profile specifies the IEEE 1588 functions that are necessary to ensure network element interoperability for the delivery of accurate phase/time (and frequency) synchronization. The profile is based on the use of partial timing support (PTS) or assisted partial timing support (APTS) from the network architecture as described in [ITU-T G.8275] and definitions described in [ITU-T G.8260].

It is assumed that this profile will be used in well-planned cases where network behaviour and performance can be constrained within well-defined limits, including limits on static asymmetry. Control of static asymmetries can be achieved in case of assisted partial timing support. Use of this profile in unassisted mode would require careful considerations on how to control static asymmetries. Additional considerations are included in [ITU-T G.8271.2]. This version of the profile specifies the high-level design requirements, modes of operation for the exchange of PTP messages, the PTP protocol mapping, the best master clock algorithm (BMCA) options, as well as the PTP protocol configuration parameters.

At the time of publication of this profile, performance analysis, network limits, and clocks used in the profile, namely boundary and slave clocks, are for further study.

This Recommendation also specifies some aspects necessary for use in a telecom environment that are outside the scope of the PTP profile but complement it.

NOTE – [b-IEEE 1588-2019] specifies a new PTP version 2.1. Based on clause 19 of [b-IEEE 1588-2019], PTP version 2.1 is inter-operable with PTP version 2.0, which is specified in IEEE Std 1588-2008 [IEEE 1588]. Therefore, it is expected that PTP version 2.1 can be used in this profile. Further details about the use of PTP version 2.1 in this Recommendation are for further study. The intention is that an ITU-T G.8275.2 implementation based on PTP version 2.1 will be compatible/inter-operable with existing deployments using PTP version 2.0, as long as no new PTP functionality that is not present in PTP version 2.0 is used.