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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter 35 Port Unicast and Multicast Flood Blocking
Configuring Port Blocking
Blocking Flooded Traffic on an Interface
Note The interface can be a physical interface (for example, GigabitEthernet 1/1) or an EtherChannel
group (such as port-channel 5). When you block multicast or unicast traffic for a port channel, it is
blocked on all ports in the port channel group.
To disable the flooding of multicast and unicast packets to an interface, perform this task:
This example shows how to block unicast and multicast flooding on a GigabitEthernet interface1/1 and
how to verify the configuration:
Switch# configure terminal
Switch(config)# interface gigabitethernet1/1
Switch(config-if)# switchport block multicast
Switch(config-if)# switchport block unicast
Switch(config-if)# end
Switch# show interface gigabitethernet1/1 switchport
Name: Gi1/3
Switchport: Enabled
<output truncated>
Port Protected: On
Unknown Unicast Traffic: Not Allowed
Unknown Multicast Traffic: Not Allowed
Broadcast Suppression Level: 100
Multicast Suppression Level: 100
Unicast Suppression Level: 100
Command Purpose
Step 1
Switch# configure terminal
Enters global configuration mode.
Step 2
Switch(config)# interface
interface-id
Enters interface configuration mode and enter the type and
number of the switchport interface (for example,
GigabitEthernet 1/1).
Step 3
Switch(config-if)# switchport block
multicast
Blocks unknown multicast forwarding to the port.
Step 4
Switch(config-if)# switchport block unicast
Blocks unknown unicast forwarding to the port.
Step 5
Switch(config)# end Returns to privileged EXEC mode.
Step 6
Switch#
show interface
interface-id
switchport
Verifies your entry.
Step 7
Switch# copy running-config startup-config
(Optional) Saves your entries in the configuration file.
