Xilinx Virtex-4 User Manual

Embedded Tri-Mode Ethernet MAC User Guide www.xilinx.com 55
UG074 (v2.2) February 22, 2010
Client Interface
R
VLAN Tagged Frames
The reception of a VLAN tagged frame (if enabled) is shown in Figure 3-21. The VLAN
frame is passed to the client to identify the frame as VLAN tagged. This is followed by the
tag control information bytes, V1 and V2. More information on the interpretation of these
bytes is described in the IEEE Std 802.3-2002 standard.
Maximum Permitted Frame Length/ Jumbo Frames
The maximum length of a frame specified in the IEEE Std 802.3-2002 standard is 1518 bytes
for non-VLAN tagged frames. VLAN tagged frames can be extended to 1522 bytes. When
jumbo frame handling is disabled and the Ethernet MAC receives a frame exceeding the
maximum legal length, EMAC#CLIENTRXBADFRAME is asserted. When jumbo frame
handling is enabled, frames longer than the legal maximum are received in the same way
as shorter frames.
For more information on enabling and disabling jumbo frame handling, see
“Configuration Registers,” page 74.
Figure 3-20: Frame Reception with In-Band FCS Field
DA SA DATAL/T FCS
ug074_3_22_080805
EMAC#CLIENTRXD[7:0]
EMAC#CLIENTRXGOODFRAME
EMAC#CLIENTRXBADFRAME
CLIENTEMAC#RXCLIENTCLKIN
EMAC#CLIENTRXDVLD
Figure 3-21: Reception of a VLAN Tagged Frame
DA SA DATAL/T
81 00 V1 V2
VLAN
Tag
ug074_3_23_080805
EMAC#CLIENTRXD[7:0]
EMAC#CLIENTRXGOODFRAME
EMAC#CLIENTRXBADFRAME
CLIENTEMAC#RXCLIENTCLKIN
EMAC#CLIENTRXDVLD
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Xilinx Virtex-4 Specifications

General

Brand	Xilinx
Model	Virtex-4
Category	Motherboard
Language	English