Time synchronization and timestamping

X2-3200G and X2-6400G feature a time synchronization port. This interface operates with 1G SFP modules. It can be configured in a rule set's Time Synchronization section.

Time synchronization port on X2-3200G

Time synchronization port on X2-6400G

The system works as a PTPv2 slave clock and will use the synchronized time to perform high quality nanosecond precision traffic timestamping for ERSPAN type 3 encapsulated traffic.

Click the Configure Time Synchronization button to configure the MAC and IP address associated with the port. Information about the internal synchronization process and its performance is then available from the Rule Set page's PTPv2 Time Synchronization table.

The System Synchronization State section provides information about the current state of synchronization. The possible states are:

• Inactive: Synchronization port is disabled;
• Freerun: Synchronization has not completed correctly and the system is timestamping with its own clock rate;
• Progress: System is synchronizing against a local master clock and is trying to rearrange its clock frequency to follow the master;
• Locked: System is synchronized against the local master clock and the timestamping clock has an average error within ±500 ns.

This view also provides information about the clock offset against the master clock and the time server's IP address.

Traffic encapsulated in an ERSPAN type 3 tunnel will include nanosecond precision timestamps. For optimal accuracy, timestamping is best used in combination with PTPv2 Time Synchronization, which disciplines the device's internal clock to ensure it does not drift from the expected time reference.

To encapsulate traffic in an ERSPAN type 3 tunnel, navigate to a rule's Advanced tab, enable Traffic Tunneling, and set Tunnel Type to ERSPAN type 3. Fill in the fields as required.

The timestamping information is embedded within the ERSPAN type 3 header.

Below is an illustration of the encapsulation of an L2 frame in an ERSPAN type 3 GRE tunnel by an X2-Series packet broker. New headers are added to the frame. The ERSPAN type 3 header contains the timestamping information.

Example content of an ERSPAN type 3 header:

The ERSPAN type 3 packet leaving the X2-Series device has the Platform ID field set to a value of 7, and the Timestamp granularity field set to a value of 11, which means nanoseconds. The Timestamp and Upper 32-bit Timestamp fields together carry the timestamp information of the packet.