Configuring Storm Control

This document describes how to configure Storm Control on the Cisco ASR 920 Series router.

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Prerequisites for Storm Control

  • Port-level storm control should be configured on EVC interfaces.

  • Storm control threshold value should be configured as CIR (bps, kbps, %).

  • Applicable to all types of Storms (unicast, broadcast, and multicast).

Restrictions for Storm control

  • Storm control is only enabled for ports with EVC configurations.

  • Storm control is specific to the Layer2 physical interfaces and port-channels; It is not supported on the Layer 3 interfaces or BDI.

  • Storm control is supported only for unknown unicast, broadcast, and unknown multicast ingress traffic; It is not supported for egress traffic.

  • Port-level storm control is supported on the router. EFP-level storm control is not supported.

  • Strom control on local connect and cross-connect is not supported.

Information on Storm Control

A storm occurs when huge amount of broadcast, multicast, or unicast packets flood the LAN, creating excessive traffic and degrading network performance. Errors in the protocol-stack implementation or in the network configuration can also cause a storm. The mechanism to prevent and control such events is known as storm control.

Storm Control monitors incoming traffic levels over a 1-second traffic storm control interval and, during the interval compares the traffic level with the traffic storm control level configured. The traffic storm control threshold level is a percentage of the total available bandwidth of the port. Each port has different storm control levels for broadcast, multicast, and unicast type of traffic.

Storm control uses rising and falling thresholds to block and then restore the forwarding of broadcast, unicast, or multicast packets.

  • The rising threshold is the traffic limit after which, that particular traffic is blocked.

  • The falling threshold is the traffic limit below which, that particular starts forwarding again, if it was already blocked.


Note
If a particular type of ingress traffic (unicast, broadcast and multicast) is more than the rising threshold configured on it, the interface goes to blocked state for that particular traffic.

Storm control prevents traffic on a LAN from being disrupted by a broadcast, multicast, or unicast storm on a port. Storm control is applicable for physical interfaces and is used to restrict the unicast, broadcast and multicast ingress traffic on the Layer2 interfaces. The feature is disabled by default on the Cisco ASR 920 Series router.

Configuring Storm Control

Before you begin

  • Configure the ports with EVC configuration.

    Note

    To disable Storm Control feature, use the no storm-control command.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface interface-id
  4. storm-control broadcast | multicast | unicast { level { rising_threshold falling_threshold | bps rising_threshold falling_threshold | pps rising_threshold falling_threshold } }
  5. storm-control action {shutdown | trap }
  6. exit

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

interface interface-id

Example:

Router# interface gigabitethernet 0/0/0

Specifies an interface type and enters interface configuration mode.

Step 4

storm-control broadcast | multicast | unicast { level { rising_threshold falling_threshold | bps rising_threshold falling_threshold | pps rising_threshold falling_threshold } }

Example:

Router# storm-control broadcast level 1 .50

Specifies the global broadcast, multicast, or unicast storm control suppression level.

  • broadcast —Configure broadcast storm control.

  • multicast —Configure multicast storm control.

  • unicast —Configure unknown unicast storm control.

  • level —Specifies the threshold levels for broadcast, multicast, or unicast traffic.

  • rising_threshold —Upper threshold level.

  • falling_threshold —Lower threshold level.

  • bps —Specifies the suppression level in bits per second.

  • pps —Specifies the suppression level in packets per second.

Step 5

storm-control action {shutdown | trap }

Example:

Router# storm control action trap

Specifies the action to take when a storm occurs on a port

  • shutdown —Disables the port during a storm. The shutdown action sets the port to shut state during a storm. The port remains in shutdown state until recovered by giving a no shutdown command when the storm goes below the configured lower threshold .

  • trap —Sends an SNMP trap. The trap action generates an SNMP trap when a storm is detected . The default is to restrict the particular ingress traffic and not to send out traps.

Step 6

exit

Example:

Router# exit

Exits interface configuration mode and returns the router to global configuration mode.

Configuration Example 



interface GigabitEthernet0/0/1
 no ip address
 negotiation auto
 storm-control broadcast level bps 50k 40k
 storm-control multicast level pps 100 90
 storm-control unicast level 1.00 0.50
service instance 1 ethernet
  encapsulation dot1q 2
  rewrite ingress tag pop 1 symmetric
  bridge-domain 1
!

Verifying Storm Control

  • Use the show storm-control command to verify the Storm Control feature configuration. 

    Router# show storm-control

Interface   Type   Filter State   Upper        Lower        Current
---------  ------   -------------  -----------  -----------  ----------
Gi0/0/0    Bcast    Forwarding          0 pps        0 pps        0 pps
Gi0/0/0    Ucast    Forwarding      80.00%       20.00%       39.99%
Gi0/0/1    Bcast    Blocking          50k bps      40k bps  362.25k bps
Gi0/0/1    Mcast    Blocking          100 pps       90 pps      265 pps
Gi0/0/1    Ucast    Blocking         1.00%        0.50%        1.28%

    Note

    With each current traffic rate under display method, the storm control blocks traffic on the interface and the current traffic rate will always show 0%.

  • Use the show storm-control command to display the storm control configurations for the configured storm type. 

    Router# show storm-control broadcast
Interface   Type   Filter State    Upper        Lower        Current
---------  ------   -------------  -----------  -----------  ----------
Gi0/0/2    Bcast    Blocking         280k pps     260k pps  284.64k pps
Te0/0/12   Bcast    Blocking        2.29g bps       2g bps    2.49g bps
Te0/0/13   Bcast    Blocking         4.6m pps     4.3m pps    4.69m pps
Po4        Bcast    Link Down         45k pps      43k pps        0 pps
Po5        Bcast    Blocking         240k pps     235k pps  241.85k pps
Router# 
Router#show storm-control unicast
Interface   Type   Filter State   Upper        Lower        Current
---------  ------   -------------  -----------  -----------  ----------
Gi0/0/2    Ucast    Blocking         290k pps     280k pps  298.19k pps
Te0/0/12   Ucast    Blocking           4m pps     3.5m pps    4.74m pps
Te0/0/13   Ucast    Blocking         4.5m pps     4.3m pps    4.91m pps
Po4        Ucast    Link Down         45k pps      43k pps        0 pps
Po5        Ucast    Blocking         250k pps     240k pps  253.36k pps
Router# 
Router#show storm-control multicast
Interface   Type   Filter State   Upper        Lower        Current
---------  ------   -------------  -----------  -----------  ----------
Gi0/0/2    Mcast    Blocking         240m bps     220m bps   260.5m bps
Te0/0/12   Mcast    Blocking        2.25g bps       2g bps    2.38g bps
Te0/0/13   Mcast    Blocking           3g bps     2.5g bps     3.3g bps
Po4        Mcast    Link Down         45k pps      43k pps        0 pps
Po5        Mcast    Blocking         200k pps     190k pps  206.28k pps
Router#

  • Use the show storm-control GigabitEthernet command to verify the Storm Control feature configuration at the interface. 

    Router # show storm control GigabitEthernet 0/0/1

Interface   Type   Filter State   Upper        Lower        Current
---------  ------   -------------  -----------  -----------  ----------
Gi0/0/1    Bcast    Blocking          50k bps      40k bps  362.25k bps
Gi0/0/1    Mcast    Blocking          100 pps       90 pps      265 pps
Gi0/0/1    Ucast    Blocking         1.00%        0.50%        1.28%

  • Use the show run interface command to verify the action trap configured on the port. 

    Router# show run interface GigabitEthernet 0/0/1

Building configuration...
Current configuration : 300 bytes
!
interface GigabitEthernet0/0/1
 no ip address
 negotiation auto
storm-control broadcast level 9.00 7.00
 storm-control action trap
 service instance trunk 1 ethernet
  encapsulation dot1q 1-200
  rewrite ingress tag pop 1 symmetric
  bridge-domain from-encapsulation
 !
end

  • The following example shows the action trap being sent when a storm is hit. 

    Router# show storm-control G 0/0/1
Interface   Type   Filter State   Upper        Lower        Current
---------  ------   -------------  -----------  -----------  ----------
Gi0/4/2    Bcast    Blocking         9.00%        7.00%       11.00%
May 29 14:46:28.008 IST: %STORM_CONTROL-3-TRAP: A packet storm was detected on Gi0/4/2. 
Sending SNMP trap

  • The following example shows the action shutdown configured. 

    Router# show run interface Gi0/0/1

Building configuration...
Current configuration : 300 bytes
!
interface GigabitEthernet0/0/1
 no ip address
 negotiation auto
storm-control broadcast level 9.00 7.00
 storm-control action shutdown
 service instance trunk 1 ethernet
  encapsulation dot1q 1-200
  rewrite ingress tag pop 1 symmetric
  bridge-domain from-encapsulation
 !
end

Additional References

Related Documents

Related Topic Document Title

Cisco IOS commands

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mcl/allreleasemcl/all-book.html

Standards and RFCs

Standard/RFC Title

No specific Standards and RFCs are supported by the features in this document.

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Feature Information for Storm Control

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Table 1. Feature Information for Storm Control

Feature Name

Releases

Feature Information

Storm Control

Cisco IOS XE Release 3.13.0S

This feature was introduced on the Cisco ASR 920 Series Aggregation Services Router (ASR-920-12CZ-A, ASR-920-12CZ-D, ASR-920-4SZ-A, ASR-920-4SZ-D).

Feature Name

Releases

Feature Information

Cisco IOS XE Release 3.14.0S

This feature was introduced on the Cisco ASR 920 Series Aggregation Services Router (ASR-920-12CZ-A, ASR-920-12CZ-D, ASR-920-4SZ-A, ASR-920-4SZ-D, ASR-920-10SZ-PD, ASR-920-24SZ-IM, ASR-920-24SZ-M, ASR-920-24TZ-M) .