Assisted Partial Timing Support on ACX7024 and ACX7024X Routers
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.
ACX7024 and ACX7024X routers act as Telecom Boundary Clock 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 by deriving the time information from a
G8275.2 packet timeReceiver. If GNSS loses lock and PTP is unavailable or not ready,
then the system moves into a holdover-in-spec state with the internal
clock and continues to be in that state until the holdover timer expires. 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 to it.
The supported APTS features include:
-
Both G.8275.1 and G8275.2 timeTransmitter ports are supported, however only a single G.8275.2 timeReceiver port can be configured as the backup path for APTS.
- Up to 512 PTPoIPv4 timeTransmitter streams are supported and up to 128 PTPoE timeTransmitter streams are supported. PTPoIPv4 and PTPoE 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.
-
Unicast negotiation is enabled by default in APTS mode.
-
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.
Configure
ptp-modeto enable PTP functionality:set chassis fpc 0 pic 0 ptp-mode
- Configure GNSS
settings:
set chassis synchronization network-option option-1 set chassis synchronization enable-extended-ql-tlv set chassis synchronization esmc-transmit interfaces all set chassis synchronization gnss-receiver 0 interface set chassis synchronization gnss-receiver 0 receiver-type tb-1 set chassis synchronization gnss-receiver 0 constellation gps l1ca
Configure PTP. Note that the
clock-modeis 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.set protocols ptp clock-mode boundary set protocols ptp profile-type g.8275.1 set protocols ptp ipv4-dscp 54 set protocols ptp slave delay-request -4 set protocols ptp slave sync-interval -4 set protocols ptp slave grant-duration 500 set protocols ptp slave interface et-0/0/18.0 unicast-mode transport ipv4 set protocols ptp slave interface et-0/0/18.0 unicast-mode clock-source 192.168.1.2 local-ip-address 192.168.1.10 set protocols ptp master interface et-0/0/0.0 unicast-mode transport ipv4 set protocols ptp master interface et-0/0/0.0 unicast-mode clock-client 10.0.0.2 local-ip-address 10.0.0.10 set protocols ptp master interface et-0/0/2.0 multicast-mode transport ieee-802.3 set protocols ptp master interface et-0/0/10.0 multicast-mode transport ieee-802.3 set protocols ptp apts
Optionally configure the domain used for APTS profile:
set protocols ptp apts domain 44
You can enable PTP on an interface that belongs to a routing instance:
set protocols ptp slave interface et-0/0/0.0 unicast-mode clock-source 192.168.1.2 local-ip-address 192.168.1.10 set routing-instances PTP-VRF instance-type virtual-router set routing-instances PTP-VRF interface et-0/0/0.0
(Optional) Configure
holdover-in-spec-durationsettings by specifying the time in minutes:set protocols ptp holdover-in-spec-duration 10
Verification
- Verify the PTP
configuration:
user@host> show ptp global-information PTP Global Configuration: Domain number : 24 Clock mode : Boundary Profile: G.8275.1 Priority Level1 : 128 Priority Level2 : 128 Local Priority : 128 Path Trace : Disabled ESMC QL From Clock Class: Enabled SNMP Trap Status : Disabled PHY Time Stamping : Enabled UTC Leap Seconds : 37 Transparent-clock-config : DISABLED Transparent-clock-status : N/A APTS : Enabled APTS Domain : 44 APTS Unicast Negotiation : Enabled Holdover-in-spec Duration: 30 minutes Slave Parameters: Sync Interval : -6 (64 packets per second - unicast request) Delay Request Interval: -6 (64 packets per second - unicast request) Announce Interval : 0 (1 packet per second - unicast request) Announce Timeout : 3 Grant Duration : 300 Master Parameters: Sync Interval : -4 (16 packets per second) Announce Interval : -3 (8 packets per second) Delay Request Timeout : <not applicable> Clock Step : one-step Arbitrary Mode : FALSE Master Parameters (G.8275.2.enh): Min Announce Interval : -3 (8 packets per second) Max Announce Interval : 0 (1 packets per second) Min Sync Interval : -7 (128 packets per second) Max Sync Interval : 0 (1 packet per second) Min Delay Response Interval : -7 (128 packets per second) Max Delay Response Interval : 0 (1 packet per second) Number of Slaves : 1 Number of Masters : 3 Number of Stateful : 0
-
Verify PTP lock status:
user@host> show ptp lock-status detail Lock Status: Lock State : INITIALIZING/FREERUN/ACQURING/PHASE ALIGNED/HOLDOVER Holdover State : In-specification/Out-of-specification (Displayed only when Lock state is HOLDOVER) Phase offset : x ns (When current source GNSS it is offset from GNSS When current source is PTP it is offset from PTP master 0 ns when PTP is inactive) State since : 2023-11-27 05:34:56 PST (00:00:54 ago) Source Details: Current Source : GNSS/PTP/NONE Primary Source : GNSS Active, Ready or Inactive Secondary Source : PTP Active, Ready or Inactive Selected PTP Master Details: Upstream Master address : 50.1.1.1 Slave interface : et-0/0/50.0 -
Verify PTP clock details by executing the
show ptp clock detailcommand. -
Verify the available upstream PTP timeTransmitter details by executing the
show ptp all-master-clock detailcommand. -
Verify PTP port details by executing the
show ptp port detailcommand. -
Verify PTP statistics details by executing the
show ptp statistics detailcommand.