Fast Ethernet Controller (FEC)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 15-37
PAUR registers. If an exact match occurs, the frame is accepted; otherwise, the microcontroller does an
individual hash table lookup using the 64-entry hash table programmed in registers, IAUR and IALR. In
the case of an individual hash match, the frame is accepted. Again, the receiver accepts or reject the frame
based on PAUSE frame detection, shown in Figure 15-28.
If neither a hash match (group or individual), nor an exact match (group or individual) occur, then If
promiscuous mode is enabled (RCR[PROM] = 1), then the frame is accepted and the MISS bit in the
receive buffer descriptor is set; otherwise, the frame is rejected.
Similarly, if the DA is a broadcast address, broadcast reject (RCR[BC_REJ]) is asserted, and promiscuous
mode is enabled, then the frame is accepted and the MISS bit in the receive buffer descriptor is set;
otherwise, the frame is rejected.
In general, when a frame is rejected, it is flushed from the FIFO.
Figure 15-28. Ethernet Address Recognition—Receive Block Decisions
Accept/Reject
Broadcast Addr
?
?
PROM = 1
?
Receive
Address
Tr ue
NOTES:
BC_REJ - field in RCR register (BroadCast REJect)
False
Tr u e
False
BC_REJ = 1
?
Frame
Hash Match
?
Exact Match
?
Pause Frame
False
False
False
False
Tr ue
Tr ue
Tr ue
Tr u e
Receive Frame
Receive Frame
Receive Frame
Receive Frame
Reject Frame
Reject Frame
PROM - field in RCR register (PROMiscous mode)
Pause Frame - valid Pause frame received
Set BC bit in RxBD
Set MC bit in RxBD if multicast
Set M (Miss) bit in RxBD
Set MC bit in RxBD if multicast
Set BC bit in RxBD if broadcast
Flush from FIFO
Flush from FIFO
Recognition
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