Ptp Clock Redundancy; Ptp Time For System Time And Oam Time; Figure 23: Boundary Clock - Alcatel-Lucent 7750 Configuration Manual

In addition, the use of port based timestamping in every network element between the grandmaster
and the end slave application is highly recommended for delivering time to meet one microsecond
accuracies required of mobile applications.
The 7750 SR always uses the frequency output of the central clock to maintain the timebase within
the node. The PTP reference into the central clock should always be enabled as an option if the
7750 is operating in 1588 Boundary Clock mode. This avoids the situation of the node entering
holdover while propagating time with 1588.

PTP Clock Redundancy

The PTP module in the router exists on the CPM. The PTP module on the standby CPM is kept
synchronized to the PTP module on the active CPM. All sessions with external ptp peers are
maintained over a CPM switchover.

PTP Time for System Time and OAM Time

PTP has the potential to provide much more accurate time into the SR OS than can be obtained
with NTP. This PTP recovered time can be made available for system time and OAM packet time
stamping to improve the accuracies of logged events and OAM delay measurements. The
mechanism to activate PTP as the source for these internal time bases is to allocate PTP as a local
7750 SR Basic System Configuration Guide
PTP
Boundary
Clock
1588v2
Grand
Master
1588v2
Grand Packet
Master Network

Figure 23: Boundary Clock

System Management
PTP
Boundary
Clock
PTP
Boundary
Clock
PTP Slave
PTP Slave
PTP Slave
OSSG741
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