Cisco WAN Switching Modules

Field Notice: BXM Logs Continuous Yellow Alarm

August 25, 1998

Products Affected

Broadband Switch Module (BXM) Trunk Cards

Problem Description

BXM continues to log "YEL alarm" while BXM is receiving the Yellow signal in the physical layer convergence procedure (PLCP) frame. This causes a flood of error messages, and affects the network management function.


"PLCP-YEL" is not an integrated alarm on the BXM card. Hence "YEL alarm In/Out Parameters", which are set by the cnflnparm command, are not effective for the BXM-T3.

The switch software currently does a periodic test on an alarmed line or trunk every 300ms. During the period of the test, the line goes into loopback; after the test, the loopback is removed. When the line is in loopback for the short duration of the test, the defect condition clears naturally. Because "PLCP YEL" is not an integrated alarm, the alarm clears at that time. After the test, when the loopback is removed, the line receives the Yellow signal from the remote and again goes into the alarm state. This occurs every 300ms (based on the loopback test period).

Problem Symptoms

The results of this issue are a flood of error messages and affected network management function.


Customers can apply the cnffunc 1 d command to fix the problem. Sample output is shown below:

bpx1 TN StrataCom BPX 15 8.4.14 July 23 1998 11:33 GMT

Index Status Function

1 Disabled Automatic TRK Loopback Test on Local/Remote Alarms
2 Enabled User Command Logging
3 Enabled Automatic Card Reset on Hardware Error
4 Enabled Card Error Record Wraparound
5 Enabled Card Test After Failure
6 Enabled Download From Remote StrataView
7 Enabled Node-by-node Upgrade Compatibility
8 Enabled Logging of conn events in local event log
9 Enabled Logging of conn events in SV+ event log
10 Enabled Force Download From a Specific IP address

Last Command: cnffunc 1 d
Next Command:

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:

Receive Email Notification For New Field Notices

Product Alert Tool - Set up a profile to receive email updates about reliability, safety, network security, and end-of-sale issues for the Cisco products you specify.