CHAPTER
12-1
Catalyst 3550 Multilayer Switch Software Configuration Guide
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12
Configuring Port-Based Traffic Control
This chapter describes how to configure the port-based traffic control features on your switch.
Note For complete syntax and usage information for the commands used in this chapter, refer to the
Catalyst 3550 Multilayer Switch Command Reference for this release.
This chapter consists of these sections:
Configuring Storm Control, page 12-1
Configuring Protected Ports, page 12-5
Configuring Port Blocking, page 12-6
Configuring Port Security, page 12-8
Displaying Port-Based Traffic Control Settings, page 12-11

Configuring Storm Control

These sections include storm control configuration information and procedures :
Understanding Storm Control, page 12-1
Default Storm Control Configuration, page 12-3
Enabling Storm Control, page 12-3
Disabling Storm Control, page 12-4

Understanding Storm Control

Storm control prevents switchports 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 or in
the network configuration can cause a storm.
Storm control (or traffic suppression) monitors incoming traffic statistics over a time period and
compares the measurement with a predefined suppression level threshold. The threshold represents the
percentage of the total available bandwidth of the port. The switch supports separate sto rm contro l
thresholds for broadcast, multicast, and unicast traff ic. If the thr eshold of a traf fic type is re ached, furt her
traffic of that type is suppressed until the incoming traffic falls below the threshold level.