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WAN Link Health SLE

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

WAN Link Health is one of the WAN Service-Level Expectations (SLEs) that you can track on the WAN SLE dashboard in the Juniper Mist™ portal. Understand what's measured by this SLE and what issues can contribute to a low SLE.

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 for Poor WAN Link Health

When the WAN Link threshold is not met, Juniper Mist classifies the issues as follows.

  • Network—Network issues affected the WAN link.

    The Network classifier has three sub-classifiers:

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

    • 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.

    • 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:

    • Cable Issues—Faulty cables affected the WAN link.

    • 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).

    • VPN—VPN performance issue occurred.

Example

WAN Link Health Example

  • Success Rate—On the left, you see that the threshold was met 100 percent of the time.

  • Timeline—In the middle, you can drag your mouse to explore this SLE over time. To adjust the scope of the timeline, use the timeline drop-down list at the top of the Monitor page. For example, set the timeline to Today, Yesterday, This Week, or a custom date range.

  • Classifiers—On the right, you see the list of classifiers for this SLE. There were no issues during the selected time period, so all these percentages are blank.

Note:

If you click the Values button above the SLE blocks, you'll see numbers instead of percentages. Instead of success rate, you'll see the average latency for the selected time period. In the Classifiers area, you'll see the total number of user minutes that were impacted by each classifier.