Troubleshooting Cisco networks is a difficult task. No matter how sound your troubleshooting methodology is or how experienced your network engineers are, many times the problem will eventually lead to a call to the Cisco Technical Assistance Center (TAC). To save time and money, it’s important to be ready with the information that TAC will require to troubleshoot your problem.

The basics
To report a problem to TAC, referred to as “opening a trouble ticket (or case)” by the TAC support staff, a few basic pieces of information are required. This information includes a Cisco contract number, a brief description of the problem, the serial number of the device or devices being reported, and contact information for the person reporting the problem. After receiving the basic information, the TAC representative will assign a call reference number and a priority number to your trouble ticket.

Based on the type of problem being reported, the TAC support agent will assign a priority to the trouble ticket. There are four priorities used to classify trouble tickets:

  • Priority 1—Production network down
  • Priority 2—Production network performance seriously degraded
  • Priority 3—Network performance degraded
  • Priority 4—Information needed on Cisco products

A TAC support engineer will forward the trouble ticket according to the priority and type of problem being reported. The TAC support engineer will review the trouble ticket and will usually request more detailed information about the problem from the contact person, so that he or she can begin troubleshooting it.

The show tech-support command
To properly begin researching a problem, TAC representatives must have a complete picture of the network and network devices they’ll be troubleshooting. This information should include any recent configuration changes, debug information, statistics from network monitors, protocol analyzer information, and the output from various show commands. To provide some of this information, Cisco has created a single command—show tech-support—that will display information from a compilation of troubleshooting commands. When you issue this command on a Cisco router, the output from 14 show commands can be captured to a file and sent to TAC for analysis. These show commands are listed below:

  • show version
  • show running-config
  • show controllers
  • show stacks
  • show interfaces
  • show diagbus
  • show buffers
  • show process memory
  • show process cpu
  • show context
  • show boot
  • show flash bootflash
  • show ip traffic
  • show controllers cbus

Gathering pertinent troubleshooting information before calling TAC can save you time and allow you to get your network up and running again quickly. Using the information you have gathered, the TAC support engineer should be able to promptly diagnose and resolve your case. For more information on TAC, check out Cisco’s Technical Assistance Center Web site.

Warren Heaton Jr., MCSE+I, CCNP, CCDP, is the Cisco Program Manager for A Technological Advantage in Louisville, KY.

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