Nokia 7210 - PTP Clock Synchronization

7210 SAS-M, T, R6, R12, Mxp, Sx, S Basic System
Configuration Guide
System Management
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6.5.8.1 PTP Clock Synchronization
The IEEE 1588v2 standard synchronizes the frequency and time from a master clock
to one or more slave clocks over a packet stream. This packet-based
synchronization can be over unicast IP/UDP unicast or Ethernet multicast.
As part of the basic synchronization timing computation, event messages are defined
for synchronization messaging between the PTP slave clock and PTP master clock.
A one-step or two-step synchronization operation can be used; the two-step
operation requires a follow-up message after each synchronization message.
During startup, the PTP slave clock receives synchronization messages from the
PTP master clock before a network delay calculation is made. Prior to any delay
calculation, the delay is assumed to be zero. A drift compensation is activated after
a number of synchronization message intervals occur. The expected interval
between the reception of synchronization messages is user-configurable.
Figure 28 shows the basic synchronization timing computation between the PTP
slave clock and PTP best master; the offset of the slave clock is shown referenced
to the best master signal during startup.
Note:
• The 7210 SAS-M supports only two-step master port operation.
• The 7210 SAS-Mxp, 7210 SAS-R6, 7210 SAS-R12, 7210 SAS-Sx 1/10GE, and
7210 SAS-T support only one-step master port operation.
• All platforms can operate slave ports that receive from a one-step or two-step master
port.