Chapter 35 Configuring Broadcast Suppression; Understanding How Broadcast Suppression Works - Cisco WS-C6506 Software Manual

Configuring Broadcast Suppression
This chapter describes how to configure broadcast suppression on the Catalyst 6500 series switches.
For complete syntax and usage information for the commands that are used in this chapter, refer to the
Note
Catalyst 6500 Series Switch Command Reference publication.
This chapter consists of these sections:
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Understanding How Broadcast Suppression Works

Broadcast and multicast suppression is not supported on the WS-X6148A-GE-TX,
Note
WS-X6148A-GE-45A, and WS-X6548-GE-TX modules.
Broadcast suppression prevents the switched ports on a LAN from being disrupted by a broadcast storm
on one of the ports. A LAN broadcast storm occurs when the broadcast or multicast packets flood the
LAN, creating excessive traffic and degrading the network performance. Errors in the protocol-stack
implementation or in the network configuration can cause a broadcast storm.
Broadcast suppression uses filtering that measures the broadcast activity on a LAN over a time period
(15264 nsec to ~1 sec) that varies based on the type of line card and speed setting on the port, and
compares the measurement with a predefined threshold. If the threshold is reached, further broadcast
activity is suppressed for the duration of a specified time period. Broadcast suppression is disabled by
default.
Figure 35-1
broadcast suppression occurs between the time intervals T1 and T2 and between T4 and T5. During those
time periods, the amount of broadcast traffic exceeded the configured threshold.
OL-8978-04
Understanding How Broadcast Suppression Works, page 35-1
Configuring Broadcast Suppression on the Switch, page 35-3
shows the broadcast traffic patterns on a port over a given period of time. In this example,
C H A P T E R
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
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