Ethernet Media Access Controller (EMAC)/ Management Data Input/Output (MDIO) Module User's Guide

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2.10.8 Promiscuous Receive Mode
Architecture
When the promiscuous receive mode is enabled by setting the RXCAFEN bit in the receive
multicast/broadcast/promiscuous channel enable register (RXMBPENABLE), nonaddress matching frames
that would normally be filtered are transferred to the promiscuous channel. Address matching frames that
would normally be filtered due to errors are transferred to the address match channel when the RXCAFEN
and RXCEFEN bits in RXMBPENABLE are set. A frame is considered to be an address matching frame
only if it is enabled to be received on a unicast, multicast, or broadcast channel. Frames received to
disabled unicast, multicast, or broadcast channels are considered nonaddress matching.
MAC control frames address match only if the RXCMFEN bit in RXMBPENABLE is set. The RXCEFEN
and RXCSFEN bits in RXMBPENABLE determine whether error frames are transferred to memory or not,
but they do not determine whether error frames are address matching or not. Short frames are a special
type of error frames.
A single channel is selected as the promiscuous channel by the RXPROMCH bit in RXMBPENABLE. The
promiscuous receive mode is enabled by the RXCMFEN, RXCEFEN, RXCSFEN, and RXCAFEN bits in
RXMBPENABLE. Table 6 shows the effects of the promiscuous enable bits. Proper frames are frames
that are between 64 bytes and the value in the receive maximum length register (RXMAXLEN) bytes in
length inclusive and contain no code, align, or CRC errors.
Table 6. Receive Frame Treatment Summary
Address Match RXCAFEN RXCEFEN RXCMFEN RXCSFEN Receive Frame Treatment
0 0 X X X No frames transferred.
0 1 0 0 0 Proper frames transferred to promiscuous channel.
0 1 0 0 1 Proper/undersized data frames transferred to
promiscuous channel.
0 1 0 1 0 Proper data and control frames transferred to
promiscuous channel.
0 1 0 1 1 Proper/undersized data and control frames
transferred to promiscuous channel.
0 1 1 0 0 Proper/oversize/jabber/code/align/CRC data frames
transferred to promiscuous channel. No control or
undersized/fragment frames are transferred.
0 1 1 0 1 Proper/undersized/fragment/oversize/jabber/code/
align/CRC data frames transferred to promiscuous
channel. No control frames are transferred.
0 1 1 1 0 Proper/oversize/jabber/code/align/CRC data and
control frames transferred to promiscuous channel.
No undersized frames are transferred.
0 1 1 1 1 All nonaddress matching frames with and without
errors transferred to promiscuous channel.
1 X 0 0 0 Proper data frames transferred to address match
channel.
1 X 0 0 1 Proper/undersized data frames transferred
to address match channel.
1 X 0 1 0 Proper data and control frames transferred to
address match channel.
1 X 0 1 1 Proper/undersized data and control frames
transferred to address match channel.
1 X 1 0 0 Proper/oversize/jabber/code/align/CRC data frames
transferred to address match channel. No control
or undersized frames are transferred.
1 X 1 0 1 Proper/oversize/jabber/fragment/undersized/code/
align/CRC data frames transferred to address
match channel. No control frames are transferred.
Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)48 SPRUEQ6 – December 2007
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