Overview Of Port-Based Traffic Control; Finding Feature Information; Information About Storm Control; Storm Control - Cisco Catalyst 2960-XR Security Configuration Manual

Overview of Port-Based Traffic Control

Overview of Port-Based Traffic Control
Port-based traffic control is a set of Layer 2 features on the Cisco Catalyst switches used to filter or block
packets at the port level in response to specific traffic conditions. The following port-based traffic control
features are supported in the Cisco IOS Release for which this guide is written:

• Storm Control

• Protected Ports
• Port Blocking
• Port Security
• Protocol Storm Protection

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not
required.

Information About Storm Control

Storm Control
Storm control prevents traffic on a LAN from being disrupted by a broadcast, multicast, or unicast storm on
one of the physical interfaces. A LAN storm occurs when packets flood the LAN, creating excessive traffic
and degrading network performance. Errors in the protocol-stack implementation, mistakes in network
configurations, or users issuing a denial-of-service attack can cause a storm.
Storm control (or traffic suppression) monitors packets passing from an interface to the switching bus and
determines if the packet is unicast, multicast, or broadcast. The switch counts the number of packets of a
specified type received within the 1-second time interval and compares the measurement with a predefined
suppression-level threshold.

How Traffic Activity is Measured

Storm control uses one of these methods to measure traffic activity:
• Bandwidth as a percentage of the total available bandwidth of the port that can be used by the broadcast,
• Traffic rate in packets per second at which broadcast, multicast, or unicast packets are received
• Traffic rate in bits per second at which broadcast, multicast, or unicast packets are received
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multicast, or unicast traffic
Configuring Port-Based Traffic Control
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