Triple-Speed Ethernet Intel® FPGA IP User Guide

ID 683402
Date 5/30/2022
Public
Document Table of Contents

4.3.4. IEEE 1588v2 Transmit Datapath

The IEEE 1588v2 feature supports 1-step and 2-step clock synchronizations on the transmit datapath.
  • For 1-step clock synchronization:
    • Timestamp insertion depends on the PTP device and message type.
    • The MAC function inserts a timestamp in the Sync PTP message if the PTP clock operates as ordinary or boundary clock.
    • Depending on the PTP device and message type, the MAC function updates the residence time in the correction field of the PTP frame when the client asserts tx_etstamp_ins_ctrl_residence_time_update. The residence time is the difference between the egress and ingress timestamps.
    • For PTP frames encapsulated using the UDP/IPv6 protocol, the MAC function performs UDP checksum correction using extended bytes in the PTP frame.
    • The MAC function re-computes and re-inserts CRC-32 into the PTP frames after each timestamp or correction field insertion.
  • For 2-step clock synchronization, the MAC function returns the timestamp and the associated fingerprint for all transmit frames when the client asserts tx_egress_timestamp_request_valid.
Table 34.  Timestamp and Correction Insertion for 1-Step Clock SynchronizationThis table summarizes the timestamp and correction field insertions for various PTP messages in different PTP clocks.
PTP Message Ordinary Clock Boundary Clock E2E Transparent Clock P2P Transparent Clock
Insert Time stamp Insert Correction Insert Time stamp Insert Correction Insert Time stamp Insert Correction Insert Time stamp Insert Correction
Sync Yes 10 No Yes 10 No No Yes 11 No Yes 11
Delay_Req No No No No No Yes 11 No No
Pdelay_Req No No No No No Yes 11 No No
Pdelay_Resp No Yes 10 11 No Yes 10 11 No Yes 11 No Yes 10 11
Delay_Resp No No No No No No No No
Follow_Up No No No No No No No No
Pdelay_Resp_Follow_Up No No No No No No No No
Announce No No No No No No No No
Signaling No No No No No No No No
Management No No No No No No No No
10 Applicable only when 2-step flag in flagField of the PTP frame is 0.
11 Applicable when you assert tx_ingress_timestamp_request_valid.

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