Licensing Requirements and Limitations for PTP

Involved Network Elements

None

Licensing Requirements

PTP is a basic feature of a switch and is not under license control.

Feature Support in V200R019C10

Only the following switch models support PTP:

S6720-HI, S6730-H, S6730S-H

For details about software mappings, visit Hardware Query Tool and search for the desired product model.

Feature Limitations

PTP Constraints

• All the intermediate devices on the PTP synchronization path must support PTP.
• Frequency signals are transmitted bidirectionally, and time signals are transmitted unidirectionally. For frequency signals, a crossover cable is required; for time signals, a straight-through cable is required.
• PTP Announce messages contain the clock attributes of the peer device to establish the master-slave hierarchy of interfaces. Therefore, prohibit a PTP interface from receiving Announce messages from different devices.

PTP Precautions

Before configuring PTP for time synchronization, ensure frequency synchronization on the entire network. To implement frequency synchronization, configure synchronous Ethernet. This chapter describes only PTP time synchronization. For details about how to configure PTP for frequency synchronization, see "Synchronous Ethernet Configuration" in Device Management.

• PTP messages are Layer 2 broadcast messages by default. If incorrect configuration is performed, loops or broadcast storms occur and downstream devices are seriously affected. To avoid broadcast storms or loops, configure VLAN or STP before enabling PTP on an interface.
• By default, a device obtains frequency signals through synchronous Ethernet and obtains time signals through PTP. When PTP is used for clock synchronization, you are advised to configure the device to obtain frequency signals and time signals through PTP.
• The switch supports PTP only after its working mode has been set to enhanced mode using the set service-mode command.