8101 Datasheet, PDF (35/172 Pages) LSI Computer Systems – Gigabit Ethernet Controller

2.7.5 MAC Control Frame Generation
The transmit MAC can automatically generate and transmit MAC control
pause frames, which are used for flow control. This function is described
in more detail in Section 2.17, “MAC Control Frames”.
2.8 Receive MAC
The receive MAC section performs the following operations to
disassemble Ethernet packets received from the receive 8B10B PCS
section:
• Strips off the preamble and SFD
• Strips off the CRC
• Checks the destination address against the address filters to
determine packet validity
• Checks frame validity against the discard conditions
• Checks the length/type field for MAC control frames
Each of the above operations can be individually disabled and altered, if
desired. The receive MAC then sends valid packets to the receive FIFO
for storage.
2.8.1 Preamble and SFD Stripping
The transmit MAC normally strips the preamble and SFD from the
receive packet. To program the controller to not strip the preamble and
SFD set the RXPRMBL bit in “Register 7–Configuration 1‚" Section 4.3.8.
When this bit is set, the preamble and SFD are left in the receive packet
and are stored in the receive FIFO as a part of the packet.
2.8.2 CRC Stripping
The receive MAC normally strips the FCS from the receive packet. To
program the controller to not strip the FCS field, set the RXCRC bit in
“Register 7–Configuration 1‚" Section 4.3.8. When this bit is set the last
four bytes of the packet containing the CRC value are left in the receive
packet and are stored in the receive FIFO as part of the packet.
Receive MAC
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