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Description
Bit
Layer 4 Filter Match
When set, this bit indicates that the received frame matches one of the enabled Layer 4 Port
Number fields. This status is given only when one of the following conditions is true:
• Layer 3 fields are not enabled and all enabled Layer 4 fields match.
• All enabled Layer 3 and Layer 4 filter fields match.
When more than one filter matches, this bit gives the layer 4 filter status of filter indicated
by Bits [27:26].
†
25
Layer 3 Filter Match
When set, this bit indicates that the received frame matches one of the enabled Layer 3 IP
Address fields.
This status is given only when one of the following conditions is true:
• All enabled Layer 3 fields match and all enabled Layer 4 fields are bypassed.
• All enabled filter fields match.
When more than one filter matches, this bit gives the layer 3 filter status of filter indicated
by Bits [27:26].
†
24
Reserved
23:15
Timestamp Dropped
When set, this bit indicates that the timestamp was captured for this frame but got dropped
in the MTL RX FIFO buffer because of overflow.
14
PTP Version
When set, this bit indicates that the received PTP message is having the IEEE 1588 version
2 format. When reset, it has the version 1 format.
13
PTP Frame Type
When set, this bit indicates that the PTP message is sent directly over Ethernet. When this
bit is not set and the message type is non-zero, it indicates that the PTP message is sent
over UDP-IPv4 or UDP-IPv6. The information about IPv4 or IPv6 can be obtained from
Bits 6 and 7.
12
Altera Corporation
Ethernet Media Access Controller
17-49
Receive Descriptor Field 4 (RDES4)
cv_54017
2013.12.30