Skip to content
Skip to search
Skip to footer

Troubleshooting TechNotes

Some links below may open a new browser window to display the document you selected.

View Documents by Topic

Basic Concepts and Maintenance

"%Error opening tftp://255.255.255.255/network config" Error Message Prevention 03/Aug/2006
Back up and Restore Configuration Files
Buffer Tuning for all Cisco Routers 17/Jun/2016
Capturing Text Output from Hyperterminal 25/Jun/2008
How to Protect Your Network Against the Nimda Virus 06/Mar/2008
How to Upgrade from ROMmon Using the Boot Image 27/Jan/2006
IPsec Troubleshooting: Understanding and Using debug Commands 10/Oct/2022
Maximum Number of Interfaces and Subinterfaces for Cisco IOS Routers: IDB Limits 24/May/2012
Performance Tuning Basics 11/Jul/2007
Prevent "Translating. domain server (255.255.255.255)" Messages after an Invalid Command is Entered on a Router
Problems Caused by Simultaneous Access to Router NVRAM 03/Aug/2006
Reset Router to Factory Defaults 18/Aug/2022
TCP and UDP Small Servers 01/Aug/2006
Understanding the Definition of bits per second (bits/sec) from the show interfaces Command Output 01/Aug/2006
Understanding the Ping and Traceroute Commands
Use NBAR and ACLs to Block the "Code Red" Worm 02/Aug/2006

Boot Failure Recovery and IOS Upgrade

High CPU Utilization

Dealing with mallocfail and High CPU Utilization Resulting From the "Code Red" Worm 20/Jun/2008
High CPU Utilization in Exec and Virtual Exec Processes 12/Dec/2008
The show processes Command
Troubleshooting High CPU Utilization Due to Interrupts 29/May/2008
Troubleshooting High CPU Utilization due to Processes 29/Sep/2008
Troubleshooting High CPU Utilization in IP Input Process 11/Feb/2019
Troubleshoot High CPU Utilization on Routers 30/Nov/2022
What Causes %SYS-3-CPUHOG Messages? 24/Jun/2008

Troubleshooting Hardware

Processor Memory Parity Errors (PMPEs) 25/May/2016
SegV Exceptions 31/May/2016
Troubleshooting Buffer Leaks 26/May/2016
Troubleshooting Memory Problems 28/Nov/2006
Troubleshooting Spurious Accesses, Alignment Errors, and Spurious Interrupts 31/May/2016
Troubleshooting Watchdog Timeouts 21/Jun/2016

Troubleshooting Router Hang and Router Crash

Creating Core Dumps 24/Jun/2008
Less Common Types of System Crashes 12/May/2016
Retrieving Information from the Crashinfo File 01/Feb/2006
Troubleshooting Bus Error Crashes 16/Jun/2016
Troubleshoot Router Crashes 18/Nov/2019
Troubleshooting Router Hangs 02/Aug/2006
Understand Software-forced Crashes 16/Jun/2016
What Causes a Router To Be Restarted By the Abort or Trace Trap Commands 29/Nov/2006

Miscellaneous

Configuring ISL Trunks on Cisco Routers 30/Aug/2005
Troubleshoot Common L2L and Remote Access IPsec VPN Issues 31/Mar/2014
Understand the NM-HDV2 IP Communications High-Density Digital Voice or Fax Network Module 10/Aug/2006
Understanding and Configuring VLAN Routing and Bridging on a Router Using the IRB Feature 31/Aug/2009
Wireless LAN Controller Module (WLCM) Configuration Examples 19/Feb/2007

Support Documentation

All Support Documentation for this Series

Troubleshooting

Password Recovery

Customers Also Viewed