Ethernet (ETH): media access control (MAC) with DMA controller
RM0090
1128/1731
DocID018909 Rev 11
Figure 360. MAC frame format
Figure 361. Tagged MAC frame format
Each byte of the MAC frame, except the FCS field, is transmitted low-order bit first.
An invalid MAC frame is defined by one of the following conditions:
•
The frame length is inconsistent with the expected value as specified by the length/type
field. If the length/type field contains a type value, then the frame length is assumed to
be consistent with this field (no invalid frame)
•
The frame length is not an integer number of bytes (extra bits)
•
The CRC value computed on the incoming frame does not match the included FCS
Pream
b
le
SFD
Destination address
Source address
MAC client length/type
MAC client data
PAD
Frame check se
q
uence
7
b
ytes
1
b
yte
6
b
ytes
6
b
ytes
2
b
ytes
46-1500
b
ytes
4
b
ytes
MSB
LSB
Bit transmission order (right to left)
Bytes within
frame transmitted
top to
b
ottom
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Pream
b
le
SFD
Destination address
Source address
Length/type = 802.1QTagType
Tag control information
MAC client length/type
MAC client data
7
b
ytes
1
b
yte
6
b
ytes
6
b
ytes
QTag Prefix
42-1500
b
ytes
2
b
ytes
MSB
LSB
Bit transmission order (r ight to left)
b
ytes within
frame transmitted
top to
b
ottom
Frame check se
q
uence
Pad
4
b
ytes
4
b
ytes
1 0 0 0 0 0 0 0 1
VLAN identifier (VID, 12
b
its)
CFI
User priority
MSB
LSB
0 0 0 0 0 0 0 0 0
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