NT-TS Time Synchronization

Time-Stamping and Time Synchronization

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Intel® PAC
Napatech SmartNIC
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User Guide

Limitation

This subsection does not apply to the Intel® PAC with Intel® Arria® 10 GX FPGA.

Description

The Napatech time synchronization (NT-TS) (see NT-TS signal) is absolute time synchronization between two NT SmartNICs. A thin coax cable is used for connecting the NT SmartNICs.
Note: NT SmartNICs only support the NT-TS signal on the internal MCX time synchronization connectors.
Note: If two or more NT SmartNICs are NT-TS time-synchronized, it is recommended that the time stamp format of the time slave SmartNIC(s) is the same as the time stamp format in the time master SmartNIC.

Time synchronization slave

When an NT SmartNIC is working as NT-TS time synchronization slave, the SmartNIC time stamp clock is hardware-synchronized to the signal on the input time synchronization connector. If no time synchronization connector is configured as input, if the time synchronization cable on the input connector is disconnected, or if the time synchronization signal fails, the SmartNIC time stamp clock is free-running based on the local oscillator in the SmartNIC. When the external master clock signal is regained, the slave clock is smoothly synchronized to the master. The convergence time to synchronization is below 30 seconds. If the skew between master and slave clock is outside a preconfigured limit (see Enabling and Disabling Time Jumps), the slave is forced into synchronization with the master (no smooth synchronization).

When the NT slave SmartNIC is connected to a master NT SmartNIC, the slave NT SmartNIC must be configured to the same time stamp format as configured on the NT master SmartNIC.

NT-TS daisy chain support

An incoming NT-TS signal on an input time synchronization connector can be repeated in exactly the same format to an output time synchronization connector.

External and SmartNIC time samples for Napatech equipment

When a free-running NT SmartNIC is connected to another NT SmartNIC on an input time synchronization connector, the free-running SmartNIC does not synchronize to the time of the other SmartNIC (external time), but samples this time and the time of the SmartNIC itself. The NT SmartNIC uses its free-running time stamp clock to time-stamp received frames.

The SmartNIC provides a synchronized set of the external time and the time of the SmartNIC itself (SmartNIC time) sampled once per second.
Note: Synchronized sets of external time and SmartNIC time can be obtained every 20 μs, depending on the setting of the HighFrequencySampling parameter in the ntservice.ini file (see DN-0449 and Getting Sets of External Time and SmartNIC Time Every 20 µs).

PPS-triggered SmartNIC clock sampling

PPS-triggered SmartNIC clock sampling (via the PPS pulse embedded in the NT-TS signal) can be used for software-based time stamp correction (using the free-running SmartNIC time stamp clock).

Guideline

NT-TS time synchronization is to be used for all scenarios involving time synchronization between NT SmartNICs within the same server.