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Assisted Partial Timing Support on ACX7024 and ACX7024X Routers

SUMMARY Assisted Partial Timing Support (APTS) is a GNSS backed by PTP delivers accurate timing and synchronization in mobile backhaul networks. This topic talks about the APTS support on ACX7024 and ACX7024X routers.

This feature is supported on Junos OS Evolved Release 24.2R2 only.

ACX7024 and ACX7024X routers act as Telecom Boundary Cloud for Assisted partial timing support (T-BC-A). The router locks to GNSS as a primary source. When GNSS loses lock, it operates in a frequency or phase backup mode from deriving time information from a G8275.2 packet timeReceiver. If GNSS loses lock and PTP is unavailable, the system moves into a holdover state with the internal clock and continues to be in that state until the holdover timer expires (default value of 5 minutes). You can configure the holdover time using the holdover-in-spec-duration option under the [set protocols ptp] hierarchy. Once GNSS is available, the router locks back into it. Supported APTS features include:

  • Both G.8275.1 and G8275.2 timeTransmitter ports are supported, however only a single G.8275.2 slave port can be configured as the backup path for APTS.

  • Up to 512 PTPoIPv4 and PTPoE timeTransmitter streams are supported simultaneously.
  • A single PTPoIPv4 timeReceiver stream is supported when APTS is configured.

  • PTPoIPv4 timeReceiver configuration is supported for interfaces that belong to a routing-instance.

  • APTS is supported for 100G, 50G, 40G, 25G, 10G, 1G ports.

    Configuration

    To support this feature on ACX7024 and ACX7024X, you need an APTS node with GNSS source configured at the [edit chassis synchronization] hierarchy level and PTP boundary clock configured at the [edit protocols ptp] hierarchy level as shown below.

    1. Configure ptp-mode to enable PTP functionality:

    2. Configure GNSS settings:
    3. Configure PTP. Note that the clock-mode is set to boundary clock and the base profile is set to G.8275.1 in this configuration for downstream timeReceivers. The configuration [set protocols ptp apts] is required when configuring boundary clock with APTS.

      You can enable PTP on an interface that belongs to a routing instance:

    4. (Optional) Configure holdover-in-spec-duration settings:

      Verification

      • Verify the PTP configuration:
      • Verify PTP lock status:

        1. When GNSS and PTP are active:

        2. When system is locking to GNSS:

        3. When system is locked to GNSS:

        4. When GNSS is lost and the system falls back to PTP:

        5. When both GNSS and PTP are inactive:

      • Verify PTP clock detail:

      • Verify PTP timeTransmitter details: