Cisco IOS Software Releases 12.1 T

Field Notice: ubr920 Router May Reload If Access List 100 or 101 is Configured

June 23, 2000

Products Affected

Cisco ubr924 Access Router

Problem Description

If a Cisco ubr920 Series router is using the affected 12.1T images, and has configured an access list with the access list number 100 or 101, the router may reload.

Cisco IOS 12.1(2)T ubr920 images were previously deferred due to defect CSCdr45850. Further investigation has determined that CSCdr45850 is not as catastrophic as first led to believe. The Cisco ubr920 images will be undeferred with a recommended workaround listed below.

Problem Symptoms

If a Cisco ubr920 series router is configured with access list, and the access-list-number is 100 or 101 , the router may reload with a crash similar to the one listed below.

*** System received a SegV exception ***
signal= 0xb, code= 0x1200, context= 0x80a93150
PC = 0x8063bb64, Vector = 0x1200, SP = 0x80bd0060
rommon 2 > context 
CPU context of the most recent exception:
PC = 0x8063bb64 MSR = 0x00009032 CR = 0x24200040 LR = 0x8063c564
CTR = 0x80232034 XER = 0x0000023e DAR = 0x0d0d0d11 DSISR = 0x0000001f
DEC = 0x7087273a TBU = 0x00000000 TBL = 0x0f78d29c IMMR = 0x02782002
R0 = 0x8063c564 R1 = 0x80bd0060 R2 = 0x80a10000 R3 = 0x00000001
R4 = 0x80a10000 R5 = 0x00000043 R6 = 0x00000000 R7 = 0xffffffff
R8 = 0x05800001 R9 = 0x80640000 R10 = 0x00000044 R11 = 0x00000014
R12 = 0x00000011 R13 = 0x020443bc R14 = 0x00000000 R15 = 0x00000000
R16 = 0x00000000 R17 = 0x00000000 R18 = 0x00000000 R19 = 0x00000000
R20 = 0x00000000 R21 = 0x00000000 R22 = 0x00000000 R23 = 0x00000000
R24 = 0x80d11f28 R25 = 0x80ae400c R26 = 0x8063bbd8 R27 = 0x8063bca0
R28 = 0x80a10000 R29 = 0x80ce2da0 R30 = 0x80c1dca4 R31 = 0x0d0d0d0d


Cisco IOS 12.1(2)T ubr920 images were deferred on May 22, 2000. Cisco has determined that the deferral is no longer required and the images can be made available with a workaround listed in the Workaround section below.



Do not use access-list-number 100 or 101. Any other access-list-number between 102-199 is acceptable.


Cisco expects to have CSCdr45850 resolved soon. To track the resolution of CSCdr45850 you can use the CCO Bug Toolkit (registered users only) or contact the Cisco TAC. You can create a "Bug Watcher Profile" with the CCO Bug Toolkit, so you will be notified of any changes on CSCdr45850.


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



CSCdr45850 (registered customers only)

SegV exception crash bringing up image

Cisco IOS Releases Affected

Cisco IOS Releases Affected

Cisco IOS Maintenance Releases Affected

Images Affected


12.1(1.5)T through *12.1(X.x)T





* Cisco expects to have CSCdr45850 resolved soon. To track the resolution of CSCdr45850 you can use the CCO Bug toolkit (registered customers only) or contact Cisco TAC.

Upgrade Program

Maintenance Solution:

To obtain the next maintenance releases follow the instructions below:

Software Downloading from CCO via World Wide Web

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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