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ETHERNET CONTROLLER
S3C2501X
7-38
Packet (Encoded on the Medium)
Added by
Transmitter,
Stripped by
Receiver
Data Frame (sent by user)
Added by transmitter
Optionaly stripped
by receiver
Preamble
S
F
D
Destination
Address
Source
Address
Length or
type
LLC data
PAD
FCS
4-byte
0 to 46-
byte
46 to 1500
-byte
2-byte
6-byte
6-byte
1
7-bit
LLC header
LLC information field
DSAP
SSAP
CTRL
IP/X.25/......
SNAP
DSAP
SSAP
CTRL
OUI
PID
IP/X.25/......
1-byte
1-byte
1-byte
3-byte
2-byte
DSAP = Destination service access point
CTRL = Control field
OUI = Origanizationally unique identifier
SFD = Starting frame delimiter
SSAP = Source service access point
SNAP = Subnetwork access protocol
PID = Protocol identifier
LLC = Logical lick control
FCS = Frame check sequence
OR
Data frame (delivered to user)
Figure 7-5. Fields of an IEEE802.3/Ethernet Frame
7.5.1.1 Options That Affect the Standard MAC Frame
— There are a number of factors and options that can affect the standard MAC frame, as described in Table 7-
2:
— Some PHYs may deliver a longer or shorter preamble.
— Short frame mode permits LLC data fields with less than 46 bytes. Options are available to suppress padding
and to support the reception of short frames.
— Long frame mode supports LLC data fields with more than 1500 bytes. An option is also available to support
to reception of long frames.
— 'No CRC' mode suppresses the appending of a CRC field.
— 'Ignore CRC' mode allows the reception of frames without valid CRC fields.
Содержание S3C2501X
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Страница 275: ...MEMORY CONTROLLER S3C2501X 5 60 NOTES ...
Страница 289: ...I2C CONTROLLER S3C2501X 6 14 NOTES ...
Страница 373: ...GDMA CONTROLLER S3C2501X 9 24 NOTES ...
Страница 435: ...I O PORTS S3C2501X 12 12 NOTES ...
Страница 463: ...ELECTRICAL DATA S3C2501X 15 6 NOTES ...