Altera Triple Speed Ethernet MegaCore Function - Manual (Page 160)

Figure 7-23: Type 1 Egress Correction Field Update
Type 1 Egress Correction Field Update, 96b, IPV4
2-step Timestamp Request,Input
tx_egress_timestamp_request_valid
tx_egress_timestamp_request_data[N:0]
2-step Timestamp Return,Output
tx_egress_timestamp_96b_valid
tx_egress_timestamp_96b_fingerprint[N:0]
tx_egress_timestamp_96b_data[95:0]
tx_egress_timestamp_64b_valid
tx_egress_timestamp_64b_fingerprint[N:0]
tx_egress_timestamp_64b_data[63:0]
1-step Timestamp Insert,Input
tx_etstamp_ins_ctrl_timestamp_insert
tx_etstamp_ins_ctrl_timestamp_format
1-step Residence Time Update,Input
tx_etstamp_ins_ctrl_residence_time_update
tx_etstamp_ins_ctrl_ingress_timestamp_96b[95:0]
tx_etstamp_ins_ctrl_ingress_timestamp_64b[63:0]
tx_etstamp_ins_ctrl_residence_time_calc_format
1-step IPv4 and IPv6 Checksum,Input
tx_etstamp_ins_ctrl_checksum_zero
tx_etstamp_ins_ctrl_checksum_correct
1-step Location Offset,Input
tx_etstamp_ins_ctrl_offset_timestamp[15:0]
Offset 1 tx_etstamp_ins_ctrl_offset_correction_field[15:0]
Offset 2 tx_etstamp_ins_ctrl_offset_checksum_field[15:0]
tx_etstamp_ins_ctrl_offset_checksum_correction[15:0]
Ingress Timestamp
Don’t-care
Don’t-care
Don’t-care
Don’t-care
Don’t-care
Don’t-care
Don’t-care
Don’t-care
Don’t-care
Figure 7-24 shows the TX timestamp signals for the second type of egress correction field update, where
the 64 bit ingress timestamp has been pre-subtracted from the correction field at the ingress port. At the
egress port, the 64 bit egress timestamp is added into the correction field and the correct residence time is
updated in the correction field. This is the example of PTP frame encapsulated over UPD/IPV6.
The tx_etstamp_ins_ctrl_residence_time_calc_format signal is driven high to indicate that this is a
64b residence time calculation. The
tx_etstamp_ins_ctrl_checksum_correct
signal is driven high to
correct the packet UPD/IPV6 checksum by updating the checksum correction field.
Altera Corporation Interface Signals
Send Feedback
7-45 IEEE 1588v2 Timestamp
UG-01008
2014.06.30