K60P100M100SF2RM Datasheet, PDF (1176/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Functional Description
Optionally, MAC frames can be VLAN-tagged with an additional four-byte field inserted
between the MAC source address and the type/length field. VLAN tagging is defined by
the IEEE P802.1q specification. VLAN-tagged frames have a maximum length of 1522
bytes, excluding the preamble and the SFD bytes.
Frame Length
7 octets
Preamble
1 octet
SFD
6 octets
Destination address
6 octets
Source address
2 octets
VLAN tag (0x8100)
2 octets
VLAN info
2 octets
Length/type
0–1500/9000 octets
Payload data
0–42 octets
Pad
4 octets
Frame check sequence (FCS)
Payload Length
Figure 44-53. VLAN-Tagged MAC Frame Format Overview
Term
Frame length
Payload length
Table 44-55. MAC Frame definition
Description
Defines the length, in octets, of the complete frame without preamble and SFD. A frame has a valid
length if it contains at least 64 octets and does not exceed the programmed maximum length
(typical 1518).
The length/type field indicates the length of the frame's payload section. The most significant byte is
sent/received first.
• If the length/type field is set to a value less than 46, the payload is padded so that the
minimum frame length requirement (64 bytes) is met. For VLAN-tagged frames, a value less
than 42 indicates a padded frame.
• If the length/type field is set to a value larger than the programmed frame maximum length
(e.g. 1518) it is interpreted as a type field.
Destination and source 48-bit MAC addresses. The least significant byte is sent/received first and the first two least
address
significant bits of the MAC address distinguish MAC frames as detailed in MAC Address Check.
Note
Although the IEEE specification defines a maximum frame
length, the MAC core provides the flexibility to program any
value for the frame maximum length.
44.4.1.1 Pause Frames
The receiving device generates a pause frame to indicate a congestion to the emitting
device, which should stop sending data.
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K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.