Single-clock PTP Profile Interworking

Single-clock PTP profile interworking allows the 7705 SAR to use G.8275.1 as a primary PTP profile while interworking with ports using alternate profiles connected to external devices. The profiles must support Ethernet encapsulation. The 7705 SAR supports one primary profile for interworking, which must be configured as G.8275.1, and up to two alternate profiles, which can be configured as either IEC/IEEE 61850-9-3 or C37.238-2017.

By default, all PTP ports use the primary profile. The port must be shut down before the profile configuration can be modified. Any port that uses an alternate profile must be shut down before the alternate profile configuration can be modified.

Only messages exchanged on interfaces using the primary profile are included in the BMCA for the PTP clock. Interfaces using an alternate profile are considered to have their master-only value set to true and ignore any Announce messages they receive.

The PTP clock follows the BMCA rules of the primary profile and updates all datasets appropriately. Interfaces using an alternate profile use the datasets of the PTP clock to populate fields in PTP messages. However, some values from the primary profile are modified because they are incompatible with values expected by the alternate profiles. The message rates used for the Announce messages may differ between profiles. The Announce rate is controlled by the log-anno-interval command configured for the profile in use. The Sync and Delay message rates are controlled by the per-port configuration.

The clockClass value in the Announce message may need to be converted (as shown in Table: ClockClass Conversion for PTP Interworking ) when interworking from a G.8275.1 primary profile to either the IEC/IEEE 61850-9-3 or C37.238-2017 alternate profile.

See IEC/IEEE 61850-9-3 and C37.238-2017 for more information about these profiles.