Altera 10-Gbps Ethernet MAC MegaCore Function Bedienungsanleitung Seite 153

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February 2014 Altera Corporation 10-Gbps Ethernet MAC MegaCore Function User Guide
A. Frame Format
A.1. Ethernet Frame
Figure A–1 shows the Ethernet frame format.
The Ethernet frame comprises the following fields:
Inter-packet gap (IPG)—an average inter-frame length of 12 octets and is
represented with the Idle control character which consists of data value 0x07.
Preamble—inserted by the MAC or the client. MAC-inserted preamble is a
maximum of 7 octets of data with value 0x55.
Start frame delimiter (SFD)—a 1-octet fixed value of 0xD5 which marks the
beginning of a frame.
Destination and source addresses—6 octets each. The least significant byte is
transmitted first.
Length or type—a 2-octet value equal to or greater than 1536 (0x600) indicates a
type field. Otherwise, this field contains the length of the payload data. The most
significant byte of this field is transmitted first.
Payload Data and Pad—variable length data and padding.
Frame check sequence (FCS)—a 4-octet cyclic redundancy check (CRC) value for
detecting frame errors during transmission.
End frame delimiter (EFD)—a 1-octet fixed value of 0xFD which marks the end of
a frame.
Figure A–1. Ethernet Frame Format
Pad (Optional)
Frame Check Sequence
Destination Address
Source Address
MAC Client Length/Type
Payload Data
7 Octets
1 Octets
2 Octets
0..1500/9600 Octets
1 Octets
6 Octets
6 Octets
4 Octets
0..46 Octets
End Frame Delimiter (EFD)
Start Frame Delimite (SFD)
Preamble
Inter-Packet Gap (IPG)
12 Octets
Frame Length
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