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Client-Supplied FCS Passing
If the GEMAC core is configured to pass the FCS field to the client (see
Registers," on page
inserted into the frame to meet Ethernet minimum frame length specifications will be left
intact and passed to the client.
Even though the FCS is passed up to the client, it is also verified by the GEMAC core, and
rx_bad_frame asserted if the FCS check fails.
VLAN Tagged Frames
Figure 5-4
is passed to the client so that the frame may be identified as VLAN tagged. This is followed
by the Tag Control Information bytes, V1 and V2. More information on the interpretation
of these bytes may be found in IEEE 802.3-2005 standard.
rx_good_frame
rx_bad_frame
42
-- DISCONTINUED PRODUCT --
78), this is handled as shown in
gmii_rx_clk
rx_data[7:0]
rx_data_valid
rx_good_frame
rx_bad_frame
Figure 5-3: Frame Reception with In-Band FCS Field
illustrates the reception of a VLAN tagged frame (if enabled). The VLAN frame
gmii_rx_clk
rx_data[7:0]
rx_data_valid
Figure 5-4: Reception of a VLAN Tagged Frame
www.xilinx.com
Chapter 5: Using the Client Side Data Path
Figure
DA
SA
L/T
81 00V1V2
DA
SA
VLAN
tag
1-Gigabit Ethernet MAC v8.5 User Guide
"Configuration
5-3. In this case, any padding
DATA
FCS
L/T
DATA
UG144 April 24, 2009
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