SMC Networks SMC TigerAccess SMC7824M/FSW - Manual (Page 551)

SWITCHPORT BLOCK
24-11
switchport block
This command prevents flooding of unknown unicast or multicast packets
to an interface. Use the no form to restore the default setting.
Syntax
[no] switchport block {unicast | multicast}
• unicast - Specifies unknown unicast packets.
• multicast - Specifies unknown multicast packets.
Command Mode
Interface Configuration (Ethernet, Port Channel)
Default Setting
Unknown unicast and multicast packets are not blocked.
Command Usage
By default, unknown unicast or multicast traffic is flooded to all ports.
This occurs if a MAC address has been timed out or not yet learned by
the switch. If this kind of traffic is flooded to an isolated port on a
private VLAN, there could be security issues.
Example
The following example blocks unknown multicast traffic on port 5:
Console(config)#interface ethernet 1/5
Console(config-if)#switchport switchport block multicast
Console(config-if)#