Cisco Nexus 7000 Series NX-OS Troubleshooting Guide -- Before Contacting Technical Support

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This article describes the steps to perform before calling for technical support for Cisco NX-OS.

Guide Contents
Troubleshooting Overview
Troubleshooting Installs, Upgrades, and Reboots
Troubleshooting Licensing
Troubleshooting VDCs
Troubleshooting CFS
Troubleshooting Ports
Troubleshooting vPCs
Troubleshooting VLANs
Troubleshooting STP
Troubleshooting Routing
Troubleshooting Unicast Traffic
Troubleshooting WCCP
Troubleshooting Memory
Troubleshooting Packet Flow Issues
Before Contacting Technical Support (this section)
Troubleshooting Tools and Methodology


Note Note: If you purchased Cisco support through a Cisco reseller, contact the reseller directly. If you purchased support directly from Cisco, contact Cisco Technical Support.

Steps to Perform Before Calling TAC

At some point, you may need to contact your technical support representative or Cisco TAC for some additional assistance. This section outlines the steps that you should perform before you contact your next level of support in order to reduce the amount of time spent resolving the issue.

Note Note: Do not reload the module or the system until you have completed Xref_Colorparanum. Some logs and counters are kept in volatile storage and will not survive a reload.

To prepare for contacting your customer support representative, follow these steps:

1. Collect the system information and configuration. You should collect this information before and after the issue has been resolved. Use one of the following three methods to gather this information:

  • Configure your Telnet or SSH application to log the screen output to a text file. Use the terminal length 0 command and then use the show tech-support details command.
  • Use the tac-pac filename command to redirect the output of the show tech-support details command to a file, and then gzip the file.
switch# tac-pac bootflash://showtech.switch1

  • If you do not specify a filename, Cisco NX-OS creates the file as volatile:show_tech_out.gz. Copy the file from the device using the procedure in the Copying Files to or from Cisco NX-OS section.

2. If an error occurs in DCNM, take a screen shot of the error. In Windows, press Alt+PrintScreen to capture the active window, or press PrintScreen to capture the entire desktop. Paste the screenshot into a new Microsoft Paint (or similar program) session and save the file.

3. Capture the exact error codes that you see in the message logs from either DCNM or the CLI.

a. Choose Event Browser in DCNM to see the recent list of messages generated.
b. Copy the error from the message log, which you can display using either the show logging log command or the show logging last number command to view the last lines of the log.

4. Answer the following questions before you contact your technical support representative:

  • On which switch or port is the problem occurring?
  • Which Cisco NX-OS software, driver versions, operating systems versions, and storage device firmware are in your fabric?
  • What is the network topology? (In DCNM, choose Topology > Save layout.)
  • Were any changes made to the environment (VLANs, adding modules, upgrades) prior to or at the time of this event?
  • Are there other similarly configured devices that could have this problem, but do not?
  • Where was this problematic device connected (which switch and interface)?
  • When did this problem first occur?
  • When did this problem last occur?
  • How often does this problem occur?
  • How many devices have this problem?
  • Were any traces or debug output captured during the problem time? What troubleshooting steps have you attempted? Which, if any, of the following tools were used?
    • Ethanalyzer, local or remote SPAN
    • CLI debug commands
    • traceroute, ping
    • DCNM tools

5. Answer the following questions if your problem is related to a software upgrade attempt:

  • What was the original Cisco NX-OS version?
  • What is the new Cisco NX-OS version?
  • Collect the output from the following commands and forward them to your customer support representative:
show install all status
show system internal log install
show system internal log install details
show log nvram

Copying Files to or from Cisco NX-OS

You may need to move files to or from the device. These files may include the log, configuration, or firmware files.

Cisco NX-OS offers a broad range of protocols to use for copying to or from the device. The device always acts as a client, so that an ftp, scp, or tftp session always originates from Cisco NX-OS and either pushes files to an external system or pulls files from an external system.

File Server:
File to be copied to the switch: /etc/hosts

The copy command supports the ftp, scp, sftp, and tftp transfer protocols as well as 12 different sources for copying files.

switch# copy ?
bootflash:      Select source filesystem
core:           Select source filesystem
debug:          Select source filesystem
ftp:            Select source filesystem
licenses:       Backup license files
log:            Select source filesystem
modflash:       Select source filesystem
nvram:          Select source filesystem
running-config: Copy running configuration to destination
scp:            Select source filesystem
sftp:           Select source filesystem
slot0:          Select source filesystem
startup-config: Copy startup configuration to destination
system:         Select source filesystem
tftp:           Select source filesystem
volatile:       Select source filesystem

You can use secure copy (scp) as the transfer mechanism, as follows:


This example copies /etc/hosts from to hosts.txt, for user user1:

switch# copy scp://user1@ bootflash:hosts.txt
user1@'s password:
hosts 100% |*****************************| 2035 00:00

This example backs up the startup-configuration to a sftp server:

switch# copy startup-config sftp://user1@ configuration.bak1
Connecting to
User1@'s password:

Tip: You should back up the startup-configuration to a server on a daily basis and prior to any changes. You could write a short script to run on Cisco NX-OS to perform a save and then a backup of the configuration. The script needs to contain two commands: copy running-configuration startup-configuration and copy startup-configuration tftp://server/name. To execute the script, use the run-script filename command.

Using Core Dumps

Core dumps contain detailed information about the system and software status prior to a crash. Use core dumps in situations where unknown problems exist. You can send core dumps to a TFTP server or to a Flash card in slot0: of the local system. You should set up your system to generate core dumps under the instruction of your technical support representative. Core dumps are decoded by technical support engineers.

Set up core dumps to go to a TFTP server so that you can e-mail these core dumps directly to your technical support representative.

Setting Up Core Dumps Using the CLI

Use the system cores command to set up core dumps on your system as follows:

switch# system cores tftp://
switch# show system cores
Cores are transferred to tftp://
Note Note: The filename (indicated by jsmith_cores) must exist in the TFTP server directory.

See Also

Before Contacting Technical Support

Further Reading

The following links contain further information on this topic from

Working with Configuration Files

External Links

External links contain content developed by external authors. Cisco does not review this content for accuracy.

Nexus: Hands on with NX-OS, Part#1

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