Cisco IGX 8400 Series Switches

Field Notice: UFM Reports UBU Errors HWY 1 or 5

September 22, 1999

Products Affected




This problem occurs more frequently with an IGX-UXM present in the same node.


This problem occurs more frequently with an IGX-UXM present in the same node.

Problem Description

The IGX node event log may contain entries similar to the one shown below:

"Info Bus A Reports 1 Error(s) on Slot 3 HWY 1 (UBU)"

If user data is not affected, then the bus errors can be ignored.

This problem only occurs when operating 9.1 or later versions of Switch Software. Versions of software prior to 9.1 do not monitor bus parity errors.


Intermittently, the NPM leaves bad parity on the cell bus. Each card is responsible for the parity on the bus during each UBU assigned to it. In this instance, the UFM is not driving any parity on the cell bus because it does not have any cells to put onto the cell bus, so the NPM's "leftover" parity is not being corrected. 9.1 Switch Software monitors and reports these parity errors in the event log. The error in the log is informational and is an annoyance rather than a data corrupting condition. This condition is not service affecting since it only occurs when an UFM has no traffic to send.

Problem Symptoms

See "Problem Description" section.


WorkAround: Issue the command cnffunc 14 d to disable logging of Bus Diagnostic Events in local event log.

Solution: Upgrade firmware to version ZAM or later for the UFM-C or YAF or later for the UFM-U.


To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.



CSCdk41427 (registered customers only)

UFM-U/C reporting (UBU) HWY 1 errors

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods: