Low Latency 40- and 100-Gbps Ethernet MAC and PHY MegaCore Function User Guide

ID 683628
Date 12/28/2017
Public
Document Table of Contents

3.2.14.2. PTP Receive Functionality

If you turn on Enable 1588 PTP in the Low Latency 40-100GbE parameter editor, the IP core provides a 96-bit (V2 format) or 64-bit timestamp with every packet on the RX client interface, whether it is a 1588 PTP packet or not. The value on the timestamp bus (rx_ingress_timestamp_96b_data[95:0] or rx_ingress_timestamp_64b_data[63:0] or both, if present) is valid in the same clock cycle as the RX SOP signal. The value on the timestamp bus is not the current timestamp; instead, it is the timestamp from the time when the IP core received the packet on the Ethernet link. The IP core captures the time-of-day from the TOD module on rx_time_of_data_96b_data or rx_time_of_day_64b_data at the time it receives the packet on the Ethernet link, and sends that timestamp to the client on the RX SOP cycle on the timestamp bus rx_ingress_timestamp_96b_data[95:0] or rx_ingress_timestamp_64b_data[63:0] or both, if present. User logic can use this timestamp or ignore it.

Figure 33. PTP Receive Block Diagram