Cisco 4500M Command Reference

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Catalyst4500 Series SwitchCiscoIOS Command Reference—Release 12.2(18)EW
78-16201-01
Chapter2Cisco IOS Commands for the Catalyst 4500 Series Switches
switchport block
switchport block
To prevent unknown multicast or unicast packets from being forwarded, use the switchport block
interface configuration command. Use the no form of this command to allow forwarding unknown
multicast or unicast packets.
switchport block {multicast | unicast}
no switchport block {multicast | unicast}
Syntax Description
Defaults Unknown multicast and unicast traffic are not blocked.
All traffic with unknown MAC addresses is sent to all ports.
Command Modes Interface configuration
Command History
Usage Guidelines You can block unknown multicast or unicast traffic on switch ports.
Blocking unknown multicast or unicast traffic is not automatically enabled on switch ports; you must
explicitly configure it.
Note For more information about blocking packets, refer to the software configuration guide for this release.
Examples This example shows how to block unknown multicast traffic on an interface:
Switch(config-if)# switchport block multicast
You can verify your setting by entering the show interfaces interface-id switchport privileged EXEC
command.
Related Commands show interfaces switchport
multicast Specifies that unknown multicast traffic should be blocked.
unicast Specifies that unknown unicast traffic should be blocked.
Release Modification
12.1(19)EW Support for this command was introduced on the Catalyst 4500 series switch.

Cisco 4500M Specifications

General

Brand	Cisco
Model	4500M
Category	Network Router
Language	English