K60P100M100SF2RM Datasheet, PDF (1190/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Functional Description
44.4.4.4 Frame Length/Type Verification: Payload Length Check
If the length/type is less than 0x600 and NLC is set, the MAC checks the payload length
and reports any error in the frame status word and interrupt bit PLR.
If the length/type is greater than or equal to 0x600, the MAC interprets the field as a type
and no payload length check is performed.
The length check is performed on VLAN and stacked VLAN frames. If a padded frame is
received, no length check can be performed due to the extended frame payload (i.e.
padded frames can never have a payload length error).
44.4.4.5 Frame Length/Type Verification: Frame Length Check
When the receive frame length exceeds MAX_FL bytes, the BABR interrupt is generated
and the RxBD[LG] bit is set.
The frame is not truncated unless the frame length exceeds the value programmed in
ENETn_FTRL[TRUNC_FL]. If the frame is truncated, RxBD[TR] is set. In addition, a
truncated frame always has the CRC error indication set (RxBD[CR]).
44.4.4.6 VLAN Frames Processing
VLAN frames have a length/type field set to 0x8100 immediately followed by a 16-Bit
VLAN control information field.
VLAN-tagged frames are received as normal frames (the VLAN tag is not interpreted by
the MAC function) and are completely (including the VLAN tag) pushed to the user
application. If the length/type field of the VLAN-tagged frame, which is found four
octets later in the frame, is less than 42, the padding is removed. In addition, the frame
status word (RxBD[NO]) indicates that the current frame is VLAN tagged.
44.4.4.7 Pause Frame Termination
The receive engine terminates pause frames and they are not transferred to the receive
FIFO. The quanta is extracted and sent to the MAC transmit path via a small internal
clock rate decoupling asynchronous FIFO.
The quanta is written only if a correct CRC and frame length are detected by the control
state machine. If not, the quanta is discarded and the MAC transmit path is not paused.
1190
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.