Assisted Partial Timing Support on ACX500 Routers Overview
The assisted partial timing support (APTS), which is a Global Navigation Satellite System (GNSS) backed by Precision Time Protocol (PTP), delivers accurate timing and synchronization in mobile backhaul networks.
The APTS feature is supported only on the Junos OS Release 12.3X54–D25 for ACX500 router.
On the ACX500 router, the APTS feature helps you to configure PTP client ports on a GNSS reference clock serving as the PTP primary.
APTS uses GNSS as the primary time reference at cell site locations, or at an aggregation point close to the cell sites. APTS uses network-based timing distribution to assist and maintain the timing during holdover periods when GNSS is unavailable.
To support this feature, 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:
GNSS configuration
[edit chassis]
synchronization {
network-option <option-1 | option-2>;
port gnss {
client {
constellation <constellation-type>;
anti-jamming;
}
}
esmc-transmit {
interface <interfaces-name>;
}
}
PTPoE Configuration
[edit protocols]
ptp {
clock-mode boundary;
slave {
interface <slave-ptp-ifl> {
multicast-mode {
transport ieee-802.3 [ link-local ] ;
}
}
}
master {
interface <master-ptp-ifl> {
multicast-mode {
transport ieee-802.3 [ link-local ] ;
}
}
}PTPoIP Configuration
[edit protocols]
clock-mode boundary;
slave {
interface <logical-interface-name> {
unicast-mode {
transport ipv4;
clock-source <remote-master-ip-address> local-ip-address <local-slave-ip-address>;
}
}
}
master {
interface <logical-interface-name>{
unicast-mode {
transport ipv4;
clock-client <remote-slave-ip> local-ip-address <local-master-ip>;
}
}
}
}The priority of clock source would be GNSS first and then PTP.
You can use the show ptp lock-status detail, show chassis synchronization extensive, and show chassis
synchronization gnss extensive show commands to monitor and
troubleshoot the configurations.