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CHAPTER
26-1
Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
26
Configuring Port-Based Traffic Control
This chapter describes how to configure the port-based traffic control features on the Catalyst 3750-E
or 3560-E switch. Unless otherwise noted, the term switch refers to a Catalyst 3750-E or 3560-E
standalone switch and to a Catalyst 3750-E switch stack.
Note For complete syntax and usage information for the commands used in this chapter, see the command
reference for this release.
This chapter consists of these sections:
• Configuring Storm Control, page 26-1
• Configuring Protected Ports, page 26-5
• Configuring Port Blocking, page 26-6
• Configuring Port Security, page 26-7
• Displaying Port-Based Traffic Control Settings, page 26-18
Configuring Storm Control
These sections contain this conceptual and configuration information:
• Understanding Storm Control, page 26-1
• Default Storm Control Configuration, page 26-3
• Configuring Storm Control and Threshold Levels, page 26-3
Understanding 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.