Chapter 29 Configuring Broadcast Suppression; Understanding How Broadcast Suppression Works - Cisco 6500 Series Software Configuration Manual

Configuring Broadcast Suppression
This chapter describes how to configure broadcast suppression on the Catalyst 6500 series switches.
Releases earlier than Release 12.1(12c)E1 support broadcast suppression. Use traffic storm control with
Release 12.1(12c)E1 and later releases (see
Note For complete syntax and usage information for the commands used in this chapter, refer to the
Catalyst 6500 Series Switch Cisco IOS Command Reference publication.
This chapter consists of these sections:
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Understanding How Broadcast Suppression Works

Broadcast suppression prevents LAN interfaces from being disrupted by a broadcast storm. A broadcast
storm occurs when broadcast or multicast packets flood the subnet, creating excessive traffic and
degrading network performance. Errors in the protocol-stack implementation or in the network
configuration can cause a broadcast storm.
Broadcast suppression uses filtering that measures broadcast activity in a subnet over a 1-second interval
and compares the measurement with a predefined threshold. If the threshold is reached, further broadcast
activity is suppressed for the duration the interval. Broadcast suppression is disabled by default.
Figure 29-1
example, broadcast suppression occurs between times T1 and T2 and between T4 and T5. During those
intervals, the amount of broadcast traffic exceeded the configured threshold.
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Understanding How Broadcast Suppression Works, page 29-1
Broadcast Suppression Configuration Guidelines and Restrictions, page 29-2
Enabling Broadcast Suppression, page 29-3
shows the broadcast traffic patterns on a LAN interface over a given interval. In this
Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
C H A P T E R
Chapter 28, "Configuring Traffic Storm
29
Control").
29-1