Texas Instruments TMS320C645x DSP manual Promiscuous Receive Mode, Receive Frame Treatment Summary

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EMAC Functional Architecture

2.10.8Promiscuous Receive Mode

When the promiscuous receive mode is enabled by setting the RXCAFEN bit in the RXMBPENABLE register, non-address 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 RXCAFEN and RXCEFEN bits are set. Address matching frames with the filter bit set (MATCHFILT = 0) are always filtered regardless of the RXCAFEN and RXCEFEN bit setting. 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 non-address matching.

MAC control frames address match only if RXCMFEN bit is set. RXCEFEN and RXCSFEN 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 field in the RXMBPENABLE register. The promiscuous receive mode is enabled by the RXCMFEN, RXCEFEN, RXCSFEN, and RXCAFEN bits in RXMBPENABLE. Table 8 shows the effects of the promiscuous enable bits. Proper frames are frames that are between 64 and RXMAXLEN bytes in length inclusive and contain no code, align, or CRC errors.

Table 8. Receive Frame Treatment Summary

		RXMBPENABLE Bits
ADDRESS MATCH	RXCAFEN	RXCEFEN	RXCMFEN	RXCSFEN	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/cod
					e/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 non-address 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.

SPRU975B –August 2006	Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)	53
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