Altera Triple Speed Ethernet MegaCore Function Bedienungsanleitung Seite 73

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IEEE 1588v2 Architecture
Figure 4-26: Overview of the IEEE 1588v2 Feature
This figure shows only the datapaths related to the IEEE 1588v2 feature.
IEEE 1588v2
Tx Logic
IEEE 1588v2
Rx Logic
PTP Software
Stack
Time-of-Day
Clock
PHY
Tx
PHY
Rx
MAC
PHY
tx_path_delay
rx_path_delay
Timestamp &
User Fingerprint
Correction
Time of Day
Timestamp Aligned to
Receive Frame
tx_egress_timestamp_request
tx_ingress_timestamp
tx_time_of_day
rx_time_of_day
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.
Altera Corporation
Functional Description
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4-37
IEEE 1588v2 Architecture
UG-01008
2014.06.30
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