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Example: Configuring Storm Control to Prevent Network Outages on EX Series Switches

 
Note

This example uses Junos OS for EX Series switches with support for the Enhanced Layer 2 Software (ELS) configuration style. If your switch runs software that does not support ELS, see Example: Configuring Storm Control to Prevent Network Outages on EX Series Switches. For ELS details, see Using the Enhanced Layer 2 Software CLI.

Storm control enables you to prevent network outages caused by broadcast storms on the LAN. You can configure storm control on an EX Series switch to rate-limit broadcast, unknown unicast, and multicast (BUM) traffic, and at a specified level and to have packets dropped when the specified traffic level is exceeded, thereby preventing packets from proliferating and degrading the LAN.

Note

On EX4300 switches, the factory default configuration enables storm control on all Layer 2 interfaces, with the storm control level set to 80 percent of the available bandwidth used by the applicable traffic streams on that interface.

This example shows how to configure storm control on an EX Series switch running Junos OS with ELS.

Requirements

This example uses the following hardware and software components:

  • One EX Series switch running Junos OS with ELS

  • Junos OS Release 13.2 or later for EX Series switches

Overview and Topology

A storm is generated when messages are broadcast on a network and each message prompts a receiving node to respond by broadcasting its own messages on the network. This, in turn, prompts further responses, creating a snowball effect and resulting in a broadcast storm that can cause network outages.

You can use storm control to prevent broadcast storms by specifying the amount, also known as the storm control level, of BUM traffic to be allowed on an interface. You specify the storm control level as the traffic rate in kilobits per second (Kbps) of the combined applicable traffic streams or as the percentage of available bandwidth used by the combined applicable traffic streams.

Storm control monitors the level of applicable incoming traffic and compares it with the level that you specify. If the combined level of the applicable traffic exceeds the specified level, the switch drops packets for the controlled traffic types. As an alternative to having the switch drop packets, you can configure storm control to have the switch shut down interfaces or temporarily disable interfaces (see the action-shutdown statement or the recovery-timeout statement) when the storm control level is exceeded.

The topology used in this example consists of one switch connected to various network devices. This example shows how to configure the storm control level on interface ge-0/0/0 by setting the level to a traffic rate of 15,000 Kbps, based on the traffic rate of the combined applicable traffic streams. If the combined traffic exceeds this level, the switch drops packets for the controlled traffic types to prevent a network outage.

Configuration

CLI Quick Configuration

To quickly configure storm control based on the traffic rate in Kbps of the combined traffic streams, copy the following command and paste it into the switch terminal window:

[edit]

set forwarding-options storm-control-profiles sc all bandwidth-level 15000
set interfaces ge-0/0/0 unit 0 family ethernet-switching storm-control sc

Step-by-Step Procedure

To configure storm control:

  1. Configure a storm control profile, sc, and specify the traffic rate in Kbps of the combined traffic streams:
    [edit]

    user@switch# set forwarding-options storm-control-profiles sc all bandwidth-level 15000
    Note

    The name of the storm control profile can contain no more than 127 characters.

  2. Bind the storm control profile, sc, to a logical interface:
    [edit]

    user@switch# set interfaces ge-0/0/0 unit 0 family ethernet-switching storm-control sc

Results

Display the results of the configuration:

Verification

Verifying That the Storm Control Configuration Is in Effect

Purpose

Confirm that storm control is limiting the rate of traffic on the interface.

Action

Use the show interfaces ge-0/0/0 detail operational mode command to view traffic statistics on the storm-controlled interface. The input rate (in bits per second) must not exceed the storm control limit.

user@switch> show interfaces ge-0/0/0 detail

Meaning

The Input bytes field shows the ingress traffic rate in bits per second (bps). The input rate is within the storm control limit of 15,000 Kbps.