82596CA Datasheet, PDF (50/76 Pages) Intel Corporation – HIGH-PERFORMANCE 32-BIT LOCAL AREA NETWORK COPROCESSOR

82596CA
RECEIVE FRAME DESCRIPTOR
Each received frame is described by one Receive Frame Descriptor (see Figure 37) Two new memory
structures are available for the received frames The structures are available only in the Linear and 32-bit
Segmented modes
Simplified Memory Structure
The first is the Simplified memory structure the data section of the received frame is part of the RFD and is
located immediately after the Length Field Receive Buffer Descriptors are not used with the Simplified struc-
ture it is primarily used to make programming easier If the length of the data area described in the Size Field
is smaller than the incoming frame the following happens
1 The received frame is truncated
2 The No Resource error counter is updated
3 If the 82596 is configured to Save Bad Frames the RFD is not reused otherwise the same RFD is used to
hold the next received frame and the only action taken regarding the truncated frame is to update the
counter
4 The 82596 continues to receive the next frame in the next RFD
Figure 37 The Receive Frame Area
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