Cisco IGX 8400 Series Switches

Field Notice: Universal Voice Module May Reset if CAS Signalling is Incorrect.

December 10, 2003

Products Affected




Loaded with firmware D.E.F or D.E.H.

Problem Description

The IGX-UVM will reset with 0B errors.


Signalling bits, commonly referred to as the ABCD bits, are normally toggled only a few times to setup or tear down a call.

This anomaly is triggered by excessive signalling transitions received from externally attached equipment such as a channel bank, private branch exchange (PBX) or test set. The Universal Voice Module (UVM) must be configured for Channel Associated Signalling (CAS) mode for this anomaly to occur. The excessive signalling results in overflow of the Digital Signal Processor (DSP) signalling buffers which causes a hardware reset.

In another scenario, excessive signalling transitions can occur if non-voice data were passed to the UVM. A common mistake made during initial installation or turn up of new services, is to run common channel signalling (CCS) such as Integrated Services Digital Network (ISDN) over a UVM line configured for CAS. Because non-voice data commonly has excessive transitioning of its bits, the UVM will mistake it for signalling bits, and cause this reset to occur.

The second most common cause of this error is the malfunctioning of the equipment attached the the UVM, commonly a PBX. If the attached equipment mistakenly causes excessive signalling transitions to be sent to the UVM, then that, too, would cause the UVM to reset

Problem Symptoms

The event log will register a reset of the UVM. User calls, if any, will be dropped. Since this anomaly is caused by misbehavior of external equipment, it is unlikely that any calls would have been established on the affected interface at that time. Below a screen capture from the dsplog command

Class  Description                                    Date      Time     
Info   UVM 14 Inserted                                02/23/99  13:04:57
Info   T1-2 14 Removed                                02/23/99  13:04:40 
Clear  Failed UVM 14 Removed                          02/23/99  13:04:40
Major  LN 14.1 Front Card Missing                     02/23/99  13:04:38
Major  UVM 14 Hardware Failure - No backup available  02/23/99  13:04:38

Also, a card error with the following string is logged.

0B 00 06 A8 01 28 00 03

Use the command dspcderrs slot# to observe any card errors.

UVM in Slot 10 : 151447 Rev EBE
Failure Type: Hardware Error
Failure Time: Feb. 23 1999 14:14:55 PST
Hardware Error Event:
0B 00 06 A8 10 AF 23 F1 00 00 00 00 00 00
|     |        |
|_____|________|____ FIFO almost full
Error Fcode:  Unknown
Failure Type: Internal

Another card error may be logged under these conditions:

This may be caused by misconfiguration (cnfln to CAS instead of
CCS for ISDN configurations), or faulty equipment.
UVM in Slot 3  : 505222 Rev DEE
Failure Type: Hardware Error
Failure Time: May  18 1999 19:46:22 EST
Hardware Error Event:
0B 00 06 A8 01 70 01 00 00 02
|     |        |   |        |
|_____|________|___|________| High priority queue full on DSP # 8
                   0100 = DSP #8
Error Fcode:  Unknown
Failure Type: Internal
Processor Number: 01
See bug CSCdm41049 - UVM card reset with hardware error.
and bug CSCdm04354  - UVM cd keeps resetting when signalling bits toggling fast

This Command: dspcderrs 3



The preferred action is to address and resolve the external signalling anomalies on the attached device. If the attached device's signalling is behaving in accordance with CAS specifications, this anomaly will not be observed.


Download firmware D.E.C. through D.E.E. Read and understand the release notes for the selected version of firmware.

It should be noted that this problem is not caused by a hardware failure. Replacing the card will not resolve this issue. Any UVM may be caused to reset due high rate of transistions of signalling bits if the UVM is loaded with firmware D.E.F or D.E.H firmware or releases D.E.B or earlier.


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



CSCdm04354 (registered customers only)

UVM cd keeps resetting when signalling bits toggling fast.

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:

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