Users Guide

The following table describes the system clock behavior depending on whether you choose PTP or NTP as the system time
source:
Table 35. System clock behavior
System time settings/time source System clock behavior
When PTP is the system time source:
○ You cannot configure the system as an NTP client.
○ If you configure the PTP clock and it is phase locked,
PTP sets the time.
○ If you do not configure the PTP clock and it is not phase
locked, the free-running system clock sets the time.
When NTP is the system time source: NTP client sets the system time. Even if the PTP clock runs
on the system, PTP does not set the system time.
When you configure NTP as a server: NTP provides the system clock. PTP or NTP can set the
system clock.
● You can configure PTP on the port-channel interface and the port-channel member interfaces.
○ Port-channel interface: If the link aggregation is between two peer nodes, configure PTP on the port-channel interface.
The forward and reverse paths must be symmetrical for PTP. In this case, the links of the port channel need not be the
same for both forward and reverse paths.
NOTE: Dell EMC recommends that you configure PTP on port-channel member interfaces.
○ Port-channel member interfaces: If the link aggregation spans across multiple nodes, configure PTP on the port-channel
member interfaces. PTP requires symmetrical forward and reverse paths. Therefore, configure PTP on the respective
port-channel member interfaces.
● If you have configured PTP on an interface and use the interface breakout command, it removes the PTP
configuration.
On boundary clocks, the interface breakout command removes the PTP port and changes the clock hierarchy.
Precision Time Protocol Limitations
10.5.1 does not support the following features:
● Multiple PTP timing domains
● Non-default VRF
● OS10 does not send PTP messages in the two-step mode. However, OS10 does support PTP port nodes that use the
two-step mode.
Hybrid clocking
OS10 supports hybrid clocking, where Synchronous Ethernet (SyncE) is used to synchronize frequency and PTP is used to
synchronize phase and Time of Day (ToD).
Use the ptp clock boundary hybrid command to enable hybrid clocking. Hybrid clocking is applicable only for PTP
boundary clock.
When PTP clock is configured in the hybrid mode, any change in the SyncE frequency lock status affects the PTP clock
synchronization. Also, the PTP clock is synchronized only when you frequency synchronie SyncE to a clock source.
OS10 supports hybrid clocking only on the following platforms:
● S5224F-ON
● S5232F-ON
● S5248F-ON
● S5296F-ON
For more information about SyncE, see Synchronous Ethernet.
Configure Precision Time Protocol
You can configure global and interface-level settings to set up the OS10 switch to function as a PTP device. Some of these
configurations have default values assigned. For a minimum configuration to set up different use cases, see:
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System management