block unknown-unicast

Blocks the unknown unicast traffic on ports, including Link Aggregation Group (LAG) ports.
Syntax
block unknown-unicast
no block unknown-unicast
Command Default

Unknown Unicast Flood Blocking (UUFB) is disabled by default.

Modes

Interface configuration mode

Usage Guidelines

UUFB is mutually exclusive with route-only feature. Either UUFB or the route-only command can be enabled at any time within a specific interface.

Use the show interfaces ethernet or show running configuration command to verify whether UUFB feature is enabled. Use the show uufb enabled-ports command to view the ports that are enabled for UUFB.

Note: UUFB blocks all the traffic if the destination MAC address is unknown, irrespective of its VLAN.
Note: Control packets are not impacted because the destination MAC addresses of control packets are multicast MAC addresses.
Note: CPU-bound traffic is not impacted because the CPU port is masked from the egress port.

The no form of the command unblocks the unknown unicast traffic.

Examples

The following example blocks the uniform unicast traffic.

device(config)# interface ethernet 1/1/1
device(config-interface-eth-1/1/1)# block unknown-unicast
device(config-interface-eth-1/1/1)# end
History
Release Version Command History
09.0.10 This command was introduced.
Parent topic: Commands A and B