Cisco WAN Switching Modules

B-Frame Parity Errors

Document ID: 10804

Updated: Oct 04, 2005



This document defines B-Frame Parity errors and explains how to get rid of them.



There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.


For more information on document conventions, refer to the Cisco Technical Tips Conventions.

What are they?

B-Frame Parity errors indicate an error in the header portion of the frame. Errors in this portion of the frame mean that the routing information in the frame has been corrupted, so the frame may not go to the correct destination. For this reason, the frames are discarded.

What do they mean?

The exact interpretation of B-Frame Parity errors varies slightly between the cards that use the Xilinx-based BIF-RX and the Monarch cards that use the SIMBA ASIC.

For the BIF-RX based cards, this error means that the first word had an error in the horizontal parity. For the SIMBA, this error means either one of the first four words had an error in the horizontal parity, or that the intermediate, vertical parity BIP-16, that covers the first seven words, had an error.

What should I do to make them go away?

They are errors on the point-to-point data path, so they fit into the general category of debug. These errors are generally seen with BIP-16 errors and can be anywhere from the BCC cross-point, backplane to the line or trunk cards. Isolation is the difficult part with these errors, due to a long path through multiple cards which is mostly entirely unique to a particular slot to slot transmission. One needs to use all information available to minimize the number of pieces of hardware that are suspect.

If multiple cards report the errors, there is a good chance that a transmit path problem exists. One clue to the source might be a particular card or port which does not show any errors, since it is less likely to send to itself.

Related Information

Updated: Oct 04, 2005
Document ID: 10804