User's Manual

CHAPTER

28-1

Catalyst 3750-X and 3560-X Switch Software Configuration Guide

OL-21521-01

Configuring Port-Based Traffic Control

This chapter describes how to configure the port-based traffic control features on the Catalyst 3750-X

or 3560-X switch. Unless otherwise noted, the term switch refers to a Catalyst 3750-X or 3560-X

stand

alone switch and to a Catalyst 3750-X switch stack.

Note For complete syntax and usage information for the commands used in this chapter, see the command

reference for this release.

• Configuring Storm Control, page 28-1

• Configuring Protected Ports, page 28-6

• Configuring Port Blocking, page 28-7

• Configuring Port Security, page 28-8

• Displaying Port-Based Traffic Control Settings, page 28-19

Configuring Storm Control

• Understanding Storm Control, page 28-1

• Default Storm Control Configuration, page 28-3

• Configuring Storm Control and Threshold Levels, page 28-3

• Default Protected Port Configuration, page 28-6

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 a

n 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.