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Troubleshooting TechNotes

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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
Characterizing and Tracing Packet Floods Using Cisco Routers 27/May/2005
Defining Strategies to Protect Against TCP SYN Denial of Service Attacks 06/Jan/2006
How to Protect Your Network Against the Nimda Virus 06/Mar/2008
How to Upgrade from ROMmon Using the Boot Image
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 a Cisco Router to Factory Default Settings
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 of the Configuration Register on All Cisco Routers
Use NBAR and ACLs to Block the "Code Red" Worm 02/Aug/2006

Boot Failure Recovery and IOS Upgrade

Cables and Specifications

CAB-X21 MT and CAB-X21 FC Serial Cable Specifications
CAB-530 MT Serial Cable Specifications
CAB-449 MT and CAB-449 FC EIA/TIA-449 Serial Cable Specifications
CAB-232 MT and CAB-232 FC EIA/TIA-232 Serial Cable Specifications
CAB-25AS-FDTE Adapter Technical Specifications 30/Jan/2006
CAB-25AS-MMOD Adapter Technical Specifications 27/Jan/2006
Cabling Guide for Console and AUX Ports
Cisco Cable Product Numbers, Part Numbers, and Descriptions 01/Aug/2006
Ethernet AUI Port, Pinouts, and Cable Specifications
Ethernet 100BaseTX and 10BaseT Cables: Guidelines and Specifications
How to Connect a KG-84A to a Cisco Serial Interface 01/Aug/2006
Serial Cable Connection Guide 01/Aug/2006
5-in-1 EIA/TIA-449 Assembly and Pinouts 01/Aug/2006
5-in-1 EIA/TIA-232 Assembly and Pinouts 04/Mar/2008
5-in-1 V.35 Assembly and Pinouts
5-in-1 X.21 Assembly and Pinouts 04/Mar/2008

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

Hardware Troubleshooting for the Cisco 7300 Series Router 06/Oct/2005
Hardware Troubleshooting Index Page 06/Apr/2022
Processor Memory Parity Errors (PMPEs) 25/May/2016
SegV Exceptions 31/May/2016
Troubleshooting Buffer Leaks 26/May/2016
Troubleshooting Ethernet Collisions 01/Aug/2006
Troubleshooting Memory Problems
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
Troubleshooting Router Crashes
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
High-Speed Serial Interface (HSSI) Design Specification
Security Reference Information 29/Jul/2003
Understanding and Configuring VLAN Routing and Bridging on a Router Using the IRB Feature 31/Aug/2009

Support Documentation

All Support Documentation for this Series

Troubleshooting

Troubleshooting Guides

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