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WAN Link Health SLE

Use the WAN Link Health SLE to assess service levels for your WAN links.

WAN Link Health is one of the Service-Level Expectations (SLEs) that you can track on the WAN SLEs dashboard in the Juniper Mist™ portal.

WAN Link Health Example
Note:

To find the WAN SLEs dashboard, select Monitor > Service Levels from the left menu, and then select the WAN button.

What Does the WAN Link Health SLE Measure?

Juniper Mist monitors the user minutes when the WAN link health meets or fails to meet the SLE threshold. Poor WAN link health lowers the device's ability to pass traffic, thus directly affecting any clients using that link.

You can click the Settings button to set the success threshold.

Classifiers

When the WAN Link threshold is not met, Juniper Mist sorts the issues into classifiers. The classifiers appear on the right side of the SLE block. In this example, 100 percent of the issues are attributed to Network. (See the classifier descriptions below the example.)

Example of WAN Link Health SLE
  • Network—Network issues affected the WAN link.

    The Network classifier has three sub-classifiers:

    • Latency—WAN link traffic showed latency. Juniper Mist calculates latency by using the average value of round-trip time (RTT) for traffic over a period of time.

    • IPSec Tunnel Down—One of the Overlay IPsec tunnels was down.

    • Jitter—The WAN link experienced jitter. Juniper Mist calculates jitter by using the variation (standard deviation) of RTT within a period of 5 to 10 minutes for a particular WAN link. We compare the calculated value with the average deviation of RTT over a day or a week.

  • Interface—Interface issues affected the WAN link. The Interface classifier has three sub-classifiers:

    • Congestion—Congestion affected the WAN link. The Congestion sub-classifier measures the number of output packet drops. When packets enter an interface, they go in a queue for buffering. When the buffer becomes full it starts to drop packets (TxDrops).

    • Cable Issues—Faulty cables affected the WAN link.

    • VPN—VPN performance issue occurred.