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Series 3: Advanced Failure Check

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Advanced Failure Check

Products Supported: AER2100, MBR1400v2, MBR1400, CBA750B, MBR1200B, IBR600, IBR650, CBR400 and CBR450. Click here to identify your router.

Firmware Version: 5.3.0 and 4.3.2 (CBR4x0 only) - for information on upgrading firmware, click here. Please note that for the CBA4x0 routers, there will be no further firmware updates, but the process defined below remains the same.

Firmware version 6.0 has been released and introduces a vastly improved GUI for all current Series 3 routers.  Cradlepoint has created new Knowledge Base articles with updated screen shots and instructions for the new GUI layout.  As a result, this article has received its final update.  To view the version of this Knowledge Base article for Firmware 6.0 and Later please click here. 


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Summary

Configuration

Troubleshooting

Related Articles


Summary

This article describes how to configure Advanced Failure Check on a Series 3 Cradlepoint router.

Advanced Failure Check lets the router to actively verify the status of its interfaces, which leads to a quicker resolution of a problem if one is found.


Configuration

Configuration Difficulty: Beginner
  • Step 1: Log into the router's Setup Page. For help with logging in please click here.
  • Step 2: Click on the Internet tab and select Connection Manager from the drop-down menu.

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  • Step 3: Select your modem within the WAN Interfaces list by clicking on its name.

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  • Step 4: Click the Edit button to open the modem's configuration screen.

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  • Step 5: Within the WAN Configuration window, click on the General Settings tab and then click the down arrow to expand the Advanced Failure Check section.

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  • Step 6: Set the desired Failure Check Interval. This determines how often the router verifies that a connection is valid on this interface. A lower value will lead to quicker detection of a potential problem, but will also use up more of the router's resources and result in higher data usage.
  • Step 7: Click the down arrow next to the Monitor while connected field to select the desired failure check method.
    • Note: For cellular modems, the recommended failure check option is Passive DNS.
    • Note: If Active Ping is used as the failure check method, the destination IP address MUST be a stable address on the internet. Recommended option is 8.8.8.8

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  • Step 8: Set the Retry Interval and Retry Count. These values determine how many packets the router sends to test the connection, and how long it waits between each packet, in a given Failure Check occurrence.
    • Higher numbers will increase the time it takes for the router to confirm the connection is down. Lower number might end up with false positives, leading the router to believe the interface is down even though it lost only a couple of packets because of a temporary blip.

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  • Step 9: Verify that Aggressive Modem Reset is enabled. Reference this article for more information.
  • Step 10: Click Submit to apply the changes.
    • NOTE: the modem may briefly disappear from the WAN Interfaces list while it loads the new settings.

Troubleshooting

Interface Disconnects

If your modem starts disconnecting after Failure Check is enabled, but you know the actual modem has an internet connection, please verify your settings.

Active Ping

  • If the ping destination IP address is unreachable, the router will think there is no internet connection. Make sure the destination IP is a valid address on the internet with guaranteed uptime.
  • Many cellular providers will see a constant stream of pings as unwanted traffic, and they will block the connection that is generating them. Try instead using Active DNS or Passive DNS as the failure check methods.

Long Check Interval

  • If the failure check interval is very long, the router might disconnect because it has to wait a very long time (number of seconds equaling [failure check interval] times [retry count] times [retry interval]) to confirm that an interface is up. If there is even one packet lost, it has to start over.

Related Articles


Published Date: 12/11/2014

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