Monitoring Troubleshooting an OSPF Network

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The show tech-support command outputs the equivalent of the show version, show running-config, show controllers, show stacks, show interfaces, show buffers, show process memory, and show process cpu EXEC commands. In addition, show tech-support also provides some platform-specific information that is not provided in the previous commands.

Specific requirements that vary depending on the situation include the following output from general and specific SHOW commands:

  show interfaces
  show controllers {serial | token | mci | cbus | fddi | cxbus | cybus}
  show processes {cpu | mem}
  show buffer
  show mem summary
  Output from protocol-specific SHOW commands:
  show protocol route
  show protocol traffic
  show protocol interfaces
  show protocol arp
  Output from protocol-specific ping and trace diagnostic tests, as appropriate
  Output from relevant debug privileged EXEC commands, as appropriate
  Network analyzer traces, as appropriate
  Core dumps obtained by using the exception dump router configuration command, or by using the write core router configuration command if the system is operational, as appropriate.

Getting the Data from Your Router

You must tailor the way you obtain information from the router to the system you are using to retrieve the information. Following are some hints for different platforms:

  PC or Macintosh. Connect a PC or Macintosh to the console port of the router and log all output to a disk file (using a terminal emulation program). The exact procedure varies depending on the communication package used with the system.
  Terminal Connected To Console Port Or Remote Terminal. The only way to get information with a terminal connected to the console port or with a remote terminal is to attach a printer to the AUX port on the terminal (if one exists) and force all screen output to go to the printer. Using a terminal is undesirable because there is no way to capture the data to a file.
  UNIX workstation. At the UNIX prompt, enter the following command script <filename>, then Telnet to the router. The UNIX script command captures all screen output to the specified file name. To stop capturing output and close the file, enter the end-of-file character (typically ^D) for your UNIX system.

How Do I Get an Exception or Core Dump?

To obtain a core dump when a router crashes, use the exception dump ip-address router configuration command (where ip-address is the address of your TFTP server). To get a core dump, add this command to your configuration: exception dump x.x.x.x, where x.x.x.x is the address of your TFTP server. The core dump will be written to <hostname>-core where <hostname> is the name of the router as given with the hostname configuration command. This will cause the router to attempt to make a core dump if it crashes. This can fail if the router is sufficiently confused. The core dump file will be the size of memory available on the processor (for example, 4MB for a CSC/3). Depending on your TFTP server, you might also have to create these files before the router can write to them. You can test this by trying the TFTP put command from a workstation. You can also test crash dumps with the EXEC command write core. This will cause the router to generate a crash dump and is useful if the router is problematic, but has not crashed.

TFTP has a problem with core dumps bigger than 16M, in which case it is recommended using rcp instead by configuring exception protocol rcp.

Cisco Connection Online (CCO)

Cisco Connection Online (CCO), formerly Cisco Information Online (CIO), is Cisco Systems’ primary, real-time support channel. Maintenance customers and partners can self-register on CCO to obtain additional content and services.

Available 24 hours a day, 7 days a week, CCO provides a wealth of standard and value-added services to Cisco’s customers and business partners. CCO services include product information, software updates, release notes, technical tips, the Bug Navigator, the Troubleshooting Engine, configuration notes, brochures, descriptions of service offerings, and download access to public and authorized files.

CCO serves a variety of users through two interfaces that are updated and enhanced simultaneously—a character-based version and a multimedia version that resides on the World Wide Web (WWW). The character-based CCO supports Zmodem, Kermit, Xmodem, FTP, Internet e-mail, and fax download options, and is excellent for quick access to information over lower bandwidths. The WWW version of CCO provides richly formatted documents with photographs, figures, graphics, and video, as well as hyperlinks to related information.

Accessing Cisco Connection Online (CCO)

You can access CCO in the following ways:

  World Wide Web.
  Modem. From North America, 408 526-8070; from Europe, 33 1 64 46 40 82. Use the following terminal settings: VT100 emulation; data bits: 8; stop bits: 1; parity: none; baud rate: up to 14.4Kbps.

For a copy of CCO’s Frequently Asked Questions (FAQ), send e-mail to For additional information, send e-mail to

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OSPF Network Design Solutions
OSPF Network Design Solutions
ISBN: 1578700469
EAN: 2147483647
Year: 1998
Pages: 200
Authors: Tom Thomas

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