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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 Getting Started with Enhanced Layer 2 Software.

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 traffic, multicast traffic, and unknown unicast traffic 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

• 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 broadcast traffic, multicast traffic, and unknown unicast 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 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:

Step-by-Step Procedure

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
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:

Physical interface: ge-0/0/0, Enabled, Physical link is Up
  Interface index: 160, SNMP ifIndex: 503, Generation: 163
  Link-level type: Ethernet, MTU: 1514, Speed: Auto, Duplex: Auto,
  BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled,
  Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled,
  Remote fault: Online
  Device flags   : Present Running
  Interface flags: SNMP-Traps Internal: 0x0
  Link flags     : None
  CoS queues     : 8 supported, 8 maximum usable queues
  Hold-times     : Up 0 ms, Down 0 ms
  Current address: b0:c6:9a:67:90:84, Hardware address: b0:c6:9a:67:90:84
  Last flapped   : 2013-05-16 22:46:42 UTC (14w3d 03:13 ago)
  Statistics last cleared: Never
  Traffic statistics:
   Input  bytes  :            312742788                  512 bps
   Output bytes  :            245552919                    0 bps
   Input  packets:              3550009                    1 pps
   Output packets:              2622101                    0 pps
   IPv6 transit statistics:
    Input  bytes  :                   0
    Output bytes  :                   0
    Input  packets:                   0
    Output packets:                   0
  Egress queues: 8 supported, 4 in use
  Queue counters:       Queued packets  Transmitted packets      Dropped packets
    0 best-effort                    0                    1                    0
    1 assured-forw                   0                    0                    0
    5 expedited-fo                   0                    0                    0
    7 network-cont                   0              2622100                    0
  Queue number:         Mapped forwarding classes
    0                   best-effort
    1                   assured-forwarding
    5                   expedited-forwarding
    7                   network-control
  Active alarms  : None
  Active defects : None
  Interface transmit statistics: Disabled