The Integrated 100G Ethernet subsystem supports 1588v2 timestamping. All the necessary signals are provided to allow external soft logic to make precise corrections to the timestamp captured by the IP. The core supports 2-step 1588v2 clocks through ingress and egress timestamp captures.
According to the IEEE 1588v2 standard, there are various PTP message encapsulations [Ref 1] . In the case of 2-step clocks, all types of encapsulation are possible with the 100G Ethernet subsystem if the design includes a PTP-specific (software) implementation.
For a 1-step clock, the encapsulation protocol (PTP message offset) must be defined. Therefore, the integrated CMAC supports the following encapsulations for 1-step operation:
• Ethernet
• IPv4 UDP
• IPv6 UDP
Inputs are provided for the timestamp offset value in the message, and for the RX path timestamp to use for the field adjustment. Further details on the function of the control inputs are found in Table: Transceiver I/O .