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How to troubleshoot a NetGuardian "Device Failure" alarm in the T/Mon

There are a variety of reasons the NetGuardian can fail to communicate with the T/Mon. Changes to your network firewall, and incorrect set-up on unit can prevent you from being able to successfully poll your NetGuardian from your T/Mon.

How to troubleshoot a NetGuardian "Device Failure" notifications:

In T/Mon Edit:

  1. Click "Devices"
  2. Locate your NetGuardian in the list of files
  3. Click "Edit Selected Devices", this will tell you how the NetGuardian is configured.

At the top of the screen it actually says "Device Polling Enabled" which means the T/Mon is trying to talk to the NetGuardian, but we know T/Mon isn't successfully communicating with NetGuardian because we're receiving a "device failure" alarm notification in the T/Mon.

  • Click "Test DCP IP" toward the bottom of the screen, to check both the settings you've configured and the IP address of your NetGuardian


If you're able to ping the IP address of the NetGuardian but the DCP poll tests fails, we recommend repeating the "Test DCP IP" test again, to rule out a possible poll failure due to heavy traffic going across your network.

If you're still receiving "DCP Poll Test Fail" notification but the IP is correctly set up:

  1. Open a command prompt
  2. Telnet into the the NetGuardian directly with the command: telnet_IPAddress_2002 (ex: telnet 2002). You'll know if your connected to the NetGuardian if it prompts you for a password
  3. Log in with your password (default password is: dpstelecom)
  4. Type capital "D" for debug

This is going to bring up debug filters. For the "DCP Poll Test Fail" issue we're currently troubleshooting, we're going to be using the DCP debug feature. DCP is the DPS internal proprietary protocol that our devices use to communicate with each other. When the T/Mon polls your NetGuardian, the T/Mon sends a request and expects a response back from the NetGuardian. When you turn on DCP debug you should see the requests come in from the T/Mon and then the response go out from the NetGuardian.

  1. Type lowercase "d" for DCP

If you notice no traffic coming into the NetGuardian,there's one of three possible reasons why this could be happening:

  • The first possible reason is the T/Mon and the NetGuardian may have a firewall that's preventing traffic from going across the port
  • The second possible reason is if the port number isn't correct. If you're sending packets to the wrong port then configured in the NetGuardian, nothing will be shown in this debug screen
  • The third option is if you have your NetGuardian's DCP polling disabled. The NetGuardian will not show any debug options.

Troubleshoot why the NetGuardian isn't responding to polls from the T/Mon:

  1. Log directly into your NetGuardian via the web interface
  2. Navigate to the "Edit" tab (green button in the menu column)
  3. Click the "System" tab
  4. Verify the DCP port numbers matches in both the T/Mon and the NetGuardian
  5. Verify the unit ID matches in both the T/Mon and the NetGuardian. If the T/Mon doesn't send a request to the right unit ID, the NetGuardian it will not respond (For this example the unit ID of the NetGuardian in the T/Mon was "1")
  6. Correct any discrepancies
  7. Click "Submit" to save your changes
  8. Click "Reboot" to reboot and write all changes to the NetGuardian

If you're in front of the NetGuardian, you'll notice the LEDs on the front of the unit while it's rebooting. The LED's will blink red/green while rebooting, then solid green, and red when the reboot is complete. This is beneficial when you have multiple NetGuaridans in a rack, you'll know exactly which NetGuardian is rebooting.

  1. Log back into your NetGuardian and confirm the changes were saved

Confirm your now receiving polls from the NetGuardian:

  1. Navigate back to your T/Mon "Edit mode" in the web interface
  2. On the "Edit Selected Devices" screen retry the "Test DCP IP" test (You should get back a "DCP Poll OK!" message)
  3. Log into the T/Mon's "Monitor mode"
  4. In the "Change of State (COS) Alarms", you'll see the "Device Failure" alarm clear