AR# 18973

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LogiCORE 10 Gigabit Ethernet MAC - What conditions will lead to the assertion of RX_BAD_FRAME and BAD_FRAME?

Description

General Description: 

What conditions lead to the assertion of BAD_FRAME in the RX_STATISTICS_VECTOR in the Gigabit Ethernet MAC core? Are the conditions the same for RX_BAD_FRAME?

Solution

The following conditions cause the assertion of BAD_FRAME: 

- FCS errors occur 

- Packets are shorter than 64 bytes (Undersize or Fragment frames) 

- Error codes occur during the packet 

- Terminate code group is corrupted 

- Jumbo frames are received when jumbo frames are not enabled 

- The Length/Type field is a "length", but the real length of the received frame does not match the value in the Length/Type field  

 

All of the above conditions also cause the assertion of RX_BAD_FRAME, which indicates to the client to drop the frame. 

 

When a Pause Control Frame passing the following checks is received, it is counted as GOOD_FRAME in the RX_STATISTICS_VECTOR but is flagged as RX_BAD_FRAME to the client: 

- The Destination Address field is matched against the MAC Control Multicast address or the configured Source Address for the MAC 

- The Length/Type field is matched against the MAC Control Type code 

 

Control Frames are the only instance when RX_BAD_FRAME does not match BAD_FRAME.

AR# 18973
Date 05/16/2014
Status Archive
Type General Article
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