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Cisco 3661 by bus error at PC 0x6955210C, address 0x0

Cisco 3661 router hanging problem .evev though console is not available needs to hard reboot.

#sh ver

Cisco Internetwork Operating System Software

IOS (tm) 3600 Software (C3660-IO3-M), Version 12.3(26), RELEASE SOFTWARE (fc2)

Technical Support:

Copyright (c) 1986-2008 by cisco Systems, Inc.

Compiled Mon 17-Mar-08 16:55 by dchih

ROM: System Bootstrap, Version 12.0(6r)T, RELEASE SOFTWARE (fc1)

COS-DADAR-3661 uptime is 1 minute

System returned to ROM by bus error at PC 0x6955210C, address 0x0

System image file is "flash:c3660-io3-mz.123-26.bin"

cisco 3660 (R527x) processor (revision 1.0) with 46080K/19456K bytes of memory.

Processor board ID JAB042387EB

R527x CPU at 225MHz, Implementation 40, Rev 10.0, 2048KB L2 Cache

Channelized E1, Version 1.0.

Bridging software.

X.25 software, Version 3.0.0.

Primary Rate ISDN software, Version 1.1.

3660 Chassis type: ENTERPRISE

1 FastEthernet/IEEE 802.3 interface(s)

65 Serial network interface(s)

2 Channelized E1/PRI port(s)

DRAM configuration is 64 bits wide with parity disabled.

125K bytes of non-volatile configuration memory.

16384K bytes of processor board System flash (Read/Write)

Configuration register is 0x2102

Hall of Fame Super Silver

Re: Cisco 3661 by bus error at PC 0x6955210C, address 0x0


The bus error mentioned in your output might be due to a software error or might be a hardware error. With the output of show version or of show tech you might be able to use the output interpreter on the Cisco web site to identify your problem.

This link is a good article on dealing with bus errors:

And if the router is covered under a maintenance plan you could open a case with TAC and have them help you to diagnose and correct the problem.



Hall of Fame Super Silver

Re: Cisco 3661 by bus error at PC 0x6955210C, address 0x0


After my first post I decided to take the show version output from your original post and put it into the output interpreter. Here is the significant part of the output:

ERROR: This router was last restarted by a bus error:

'bus error at PC 0x6955210C, address 0x0'

The system encounters a bus error when the processor tries to access a memory location

that either does not exist (a software error) or does not respond properly (a hardware


TRY THIS: Issue a 'show region' and check if the address location (the 'address'

part of the bus error - 0x0) falls within an existing address range. If the address

reported by the bus error does not fall within the ranges displayed in the 'show

region' output, this means that the router was trying to access an invalid address.

This indicates that it is a Cisco IOS Software problem. Paste the output from the

'show stacks' command to decode the output and identify the Cisco IOS Software

bug that is causing the bus error. If the address falls within one of the ranges

in the 'show region' output, it means that the router was accessing a valid memory

address, but the hardware corresponding to that address is not responding properly.

This indicates a hardware problem. Try reseating the hardware belonging to this

address range before attempting to replace it. Use the Troubleshooting Bus Error

Crashes document for additional assistance.