Router Health SLE

What Does the Router Health SLE Measure?

The Router Health SLE measures the percentage of time when the router health was optimal and is a measure of its ability to transmit and to receive traffic.

Classifiers

A classifier is a parameter that indicates whether a router is performing optimally. When the router health's success threshold is not met, Juniper Mist Routing Assurance collects and classifies the factors contributing to failures, into classifiers. The router health SLE monitors the following classifiers (also referred to as health indicators):

• Router Unreachable─The router unreachable classifier measures the duration for which the router was unreachable. Use this classifier to know the percentage (ranging from 0 through 100) of time, router unreachability contributed to a lower Router Health SLE score.

• Network─The network classifier monitors minutes when the throughput is lower than expected due to uplink capacity limitations. It identifies issues based on the round-trip time (RTT) value of packets sent from the router to the cloud. The Network classifier has two sub-classifiers that help you identify these issues:

  • WAN Jitter─Displays minutes affected by jitter. The jitter value is calculated by comparing the standard deviation of RTT within a small period (last 5 or 10 minutes) with the overall deviation of RTT over a longer period (day or week). Use this classifier to know the percentage of time (ranging from 0 through 100) network jitter contributed to failed router's health.

  • WAN Latency─Displays minutes affected by latency. The latency value is calculated based on the average value of RTT over a period of time. Use this classifier to know the percentage of time (ranging from 0 through 100) network latency contributed to failed router's health.

  Note:

  If a router is unreachable for more than two days, then it stops contributing any bad minutes to the Router Health SLE. Once the router is reconnected to Juniper Mist Routing Assurance, it will start contributing to the SLE again.

• System─The System classifier has three sub-classifiers that help you identify these issues:

  • CPU─CPU consumption of a router. Use this classifier to know the percentage of time (ranging from 0 through 100) system CPU utilization contributed to failed router's health.

    Configuration commits, BGP peer down, and BGP flapping are some of the reasons for CPU consumption spiking up.

    Note:

    The CPU classifier has a threshold value of 90 percent.

  • Temperature─Temperature of a router. Use this classifier to know the percentage of time (ranging from 0 through 100) system temperature contributed to failed router's health. Failure of the cooling system or environmental factors could impact this classifier.

  • Memory─Memory consumption of a router. Use this classifier to know the percentage of time (ranging from 0 through 100) system memory contributed to failed router's health.

    Note:

    The Memory classifier has a threshold value of 90 percent.

• Capacity─The Capacity classifier monitors the highest usage capacity of routing on a router which includes the highest usage of the Routing Information Base (RIB) vs. the Forwarding Information Base (FIB), the highest usage within FIBs and, the highest usage of FIBs across all the FPCs and Packet Forwarding Engines (PFE). The Capacity classifier has two sub-classifiers:

  • Route Table─The Route Table Capacity is the highest utilization of RIB and FIB. This sub-classifier displays the percentage of time (ranging from 0 through 100) the capacity of the route table contributed to failed router's health.

    Note:

    See Routing Table Capacity to view RIB and FIB usage separately.

    Note:

    The Route Table sub-classifier has a threshold value of 80 percent.

  • ARP Table─The ARP Table Capacity of the Address Resolution Protocol (ARP) table. This sub-classifier displays the percentage of time (ranging from 0 through 100) the capacity of the ARP table contributed to failed router's health.

    Note:

    The ARP Table sub-classifier has a threshold value of 80 percent.

  When you see a high amount of capacity usage, you must check the peer usage and the number of routes on each peer for that router. If you find any outliers here, contact your Juniper Support representative to resolve the issue.

In Figure 1, the Router Health SLE met the service level goal for more than 99 percent of the time and Router Unreachable classifier contributed to failed router health 100 percent of the time. The network, system and capacity classifiers were at their best with 0 percent severity.

Analyze Router Health SLE Score

The root cause analysis page provides visualizations for distribution, timeline, statistics for service level failures and enables administrators to understand the scope of these issues.

Click the View Insights Tab to navigate to the Insights tab which gives you fine-grained details of the router events. You can now use the Insights tab to correlate router events that could have impacted the SLE. For example, a Config Changed router event might have caused the CPU to spike up during a specific period. A Router Disconnected router event might have contributed to Router Unreachable.

Click the SLE or a classifier to navigate to the root cause analysis page.

• Statistics─The Statistics Tab displays the success rate of the SLE metric. Administrators can also view the distribution graph to understand the severity of the SLE with its impact duration.

  Figure 2: Root Cause Analysis of SLE Score

• Timeline─The Timeline graph represents the trend of SLE failure minutes over a time period. You can move the slider across the graph.

  You can view the timeline graph for an SLE, a classifier and also for a sub-classifier. As you mouse over the graph, a pop-up on the slider displays the failure minutes of every classifier and sub-classifier during the time period. Colored vertical bars on the graph indicate various classifiers and sub-classifiers.

  You can view the graph legend on the graph to interpret the plotted lines. Drag an area of interest to zoom in to the graph.

  Figure 3: Timeline

• Distribution─Use the distribution Tab to analyze service level failures by various attributes such as overall impact, failure rate and anomaly. The distribution Tab displays these attributes for all the routers connected at the selected site.

  You can sort the columns in the table by the column header. Click any column header to sort its entries. By default, the attributes are sorted by most anomalous.

  describes the fields on the Distribution tab.

  Table 1: Fields on the Distribution Tab

  Fields	Description
  Name	Name of the Router.
  Overall Impact	Router's contribution (in percentage) to the SLE failure.
  Failure Rate	Router failure rate (in percentage).
  Anomaly	Factor by which a router failed to meet the service level goal.

  Figure 4: Distribution

• Affected Items─The Affected items Tab lists all routers that failed to meet the service level goal. From this Tab, you can view affected routers' details such as MAC address, model number, failure rate and so on. The affected item Tab also displays the count of routers that failed to meet the service level goal.

  You can sort the columns in the table by the column header. Click any column header to sort its entries. Table 2 describes the fields on the Affected Items tab.

  Click a router to view the RCA for a specific router. The RCA page now displays the SLE metrics for the router. Click the View Insights Tab to navigate to the Router Insights page. Use the Router Charts, the Router Interface Queues, and the BGP summary information of the router to debug the issues further.

  Table 2: Fields on Affected Items Tab

  Fields	Description
  Name	Name of the Router.
  MAC	MAC address of the router.
  Overall Impact	Router's contribution (in percentage) to the SLE failure.
  Failure Rate	Router failure rate (in percentage).
  Model	Router model name.
  Version	Version of Junos OS or Junos OS Evolved running on the router.

  Figure 5: Affected Items