Xilinx Virtex-4 User Manual

Embedded Tri-Mode Ethernet MAC User Guide www.xilinx.com 41
UG074 (v2.2) February 22, 2010
Client Interface
R
In-Band Parameter Encoding
The Ethernet MAC frame parameters, destination address, source address, length/type,
and the FCS are encoded within the same data stream used to transfer the frame payload
instead of separate ports. This provides the maximum flexibility in switching applications.
Padding
When fewer than 46 bytes of data are supplied by the client to the Ethernet MAC, the
transmitter module adds padding – up to the minimum frame length. However, if the
Ethernet MAC is configured for client-passed FCS, the client must also supply the padding
to maintain the minimum frame length (see “Client-Supplied FCS Passing,” page 41).
Client-Supplied FCS Passing
In the transmission timing case shown in Figure 3-4, an Ethernet MAC is configured to
have the FCS field passed in by the client (see “Configuration Registers,” page 74). The
client must ensure that the frame meets the Ethernet minimum frame length requirements;
the Ethernet MAC does not pad the payload.
Figure 3-4: Frame Transmission with Client-Supplied FCS
DA SA DATA F C SL/T
EMAC#CLIENTTXCOLLISION
ug074_3_06_072705
CLIENTEMAC#TXCLIENTCLKIN
CLIENTEMAC#TXD[7:0]
CLIENTEMAC#TXDVLD
EMAC#CLIENTTXACK
CLIENTEMAC#TXFIRSTBYTE
CLIENTEMAC#TXUNDERRUN
EMAC#CLIENTTXRETRANSMIT
EMAC#PHYTXCHARISK
(SGMII or 1000BASE-X
PCS/PMA only)
EMAC#PHYCHARDISPMODE
(SGMII or 1000BASE-X
PCS/PMA only)
EMAC#PHYTXD[7:0]
(SGMII or 1000BASE-X
PCS/PMA only)
/T/ /R/
PRE
/S/
/I1/ /I2/ /I2/ /I2/ /I2/
FCS
SFD
/I1/
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Xilinx Virtex-4 Specifications

General

Brand	Xilinx
Model	Virtex-4
Category	Motherboard
Language	English