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Wired Throughput SLE

SUMMARY Use the Wired Throughput SLE to assess users' experiences with throughput on your wired network.

Throughput is one of the Service-Level Expectations (SLEs) that you can track on the wired SLEs dashboard.

Wired Throughput SLE Example
Note:

To find the Wired SLEs dashboard, select Monitor > Service Levels from the left menu of the Juniper Mist™ portal, and then select the Wired button.

What Does the Wired Throughput SLE Measure?

Juniper Mist measures the available bandwidth on your network. This SLE can help you to determine if you need more wired bandwidth on your site.

Classifiers

When the throughput 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, less than 1 percent of the issue were attributed to Congestion Uplink, 19 percent to Interface Anomalies, 1 percent to Storm Control, and 80 percent to Congestion. (See the classifier descriptions below the example.)

Wired Throughput SLE Example
  • Congestion Uplink—The SLE dashboard shows high congestion uplink when:

    • One of the neighbors is a switch or a router (known through LLDP).

    • The port is a Spanning Tree Protocol (STP) root port.

    • The uplink port has a higher number of transmitted and received packets compared to the other ports.

    • Aggregated Links. Congestion can also be caused by aggregated Ethernet links and module ports.

  • Interface Anomalies—The details for interface anomalies are all obtained from the switch. The Interface Anomalies classifier contains three sub-classifiers: MTU Mismatch, Cable Issues, and Negotiation Failed.

    • MTU Mismatch—As an administrator, you can set an MTU value for each interface. The default value for Gigabit Ethernet interfaces is 1514 . To support jumbo frames, you must configure an MTU value of 9216, which is the upper limit for jumbo frames on a routed virtual LAN (VLAN) interface. It's important to ensure that the MTU value is consistent along the packet's path, as any MTU mismatch will result in discarded or fragmented packets. In Juniper Networks switches, you can check for MTU mismatches in the MTU Errors and Input Errors sections of the show interface extensive command output. Each input error or MTU error contributes to a "bad user minute" under MTU mismatch.

    • Cable Issues—This sub-classifier shows the user minutes affected by faulty cables in the network.

    • Negotiation Failed—Latency on ports can happen due to autonegotiation failure, duplex conflicts, or user misconfiguration of device settings. Moreover, older devices may fail to achieve maximum speed and could operate at a slower link speed of 100 Mbps. This sub-classifier identifies and helps mitigate instances of bad user time caused by these issues.

  • Storm Control—Storm control allows the device to monitor traffic levels and drop broadcast, unknown unicast, and multicast packets when they exceed a set threshold or traffic level. This threshold is known as a storm control level or storm control bandwidth. The default storm control level is 80 percent of the combined broadcast, multicast, and unknown unicast traffic on all Layer 2 interfaces of Juniper switches. Storm control helps prevent traffic storms, but it can also potentially throttle applications or client devices. This classifier identifies these conditions and helps users proactively mitigate throughput issues.

  • Congestion—This classifier measures the number of output drops. When packets come into a switch interface, they are placed in an input queue (buffer). When the buffer becomes full, it will start to drop packets (TxDrops). We use a formula that takes into account the following ratios to determine if there is a 'bad user minute' due to congestion:

    • TxDrops to TxPackets—Total transmitted bytes dropped to total packets transmitted.

    • Txbps to Link speed—Total bytes transmitted per second to link speed.

    • RxSpeed to Link speed—Total bytes received per second to link speed.

  • Network—You can use this classifier to monitor user 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 switch to the Mist cloud. The Network classifier has two sub-classifiers that help you identify these issues:

    • Latency—Displays user minutes affected by latency. The latency value is calculated based on the average value of RTT over a period of time.

    • Jitter—Displays user 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). You can view this information for a particular switch or site.