Enabling CFM on a link

When CFM is enabled for a link, the CPE device sends control packets over that link only. When you enable CFM for a link, you must also enable CFM on the opposite-direction link.

To enable CFM on a link:

  1. Enable CFM on the link in one of the following ways:
    • If you want to enable CFM for a link that was established from a CPE device, go to the SD-WAN → CPE section, click the CPE device, select the Links tab, and click Management → Set CFM next to the link.
    • If you want to enable CFM for one of the links in the table of all links, go to the Infrastructure section, click Management → Configuration menu next to the controller, go to the Links section, and click Management → Set CFM next to the link.
  2. If you want to enable CFM for one of the links in the graphic topology with all links, go to the Infrastructure section, click Management → Configuration menu next to the controller, go to the Topology section, click the link, and click Set CFM.
  3. This opens a window, in that window, select the Override check box. This check box is cleared by default.
  4. Select Save for both links to enable CFM on the opposite-direction link. This check box is cleared by default.
  5. In the CFM drop-down list, select Enabled. The default value is Disabled.
  6. In the Interval drop-down list, select the time interval for sending control packets:
    • 300 ms.
    • 1 s. Default value.
    • 10 s.
    • 1 min.

    The response timeout is equal to the control packet sending interval times 3.5. The time it takes to switch a CPE device over to a new connection when no response packets are received is equal to the control packet sending interval multiplied by a number in the range from 3.5 to 7. For example, if in the Interval drop-down list, you selected 300 ms, the response timeout is 1.05 seconds, and the time it takes to switch the CPE device to a new link is 1.05 to 2.1 seconds.

    The time interval for sending control packets set for the link overrides the time intervals for sending control packets that you specified when enabling CFM on CPE devices. For example, if in the Interval drop-down list for CPE 1, you selected 300 ms, for CPE 2 you selected 1 s, and for the link between CPE 1 and CPE 2 you selected 10 s, the resulting time interval for sending control packets is 10 seconds.

  7. Click Save.

    CFM is enabled for the link.

  8. If you enabled CFM for a link established from the CPE device, click Save in the upper part of the settings area to save the CPE device settings.
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