Blocking Flooded Traffic On A Port - Cisco WS-C2950-24 Configuration Manual

Configuring Flooding Controls

Blocking Flooded Traffic on a Port

Command
Step 1
configure terminal
Step 2
interface interface
Step 3 port block multicast
Step 4
port block unicast
Step 5 end
Step 6
show port block {multicast |
unicast} interface
Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
7-6
By default, the switch floods packets with unknown destination MAC addresses
to all ports. Some configurations do not require flooding. For example, a port that
has only manually assigned addresses has no unknown destinations, and flooding
serves no purpose. Therefore, you can disable the flooding of unicast and
multicast packets on a per-port basis. Ordinarily, flooded traffic does not cross
VLAN boundaries, but multi-VLAN ports flood traffic to all VLANs they belong
to.
Beginning in privileged EXEC mode, follow these steps to disable the flooding of
multicast and unicast packets to a port:
Purpose
Enter global configuration mode.
Enter interface configuration mode, and enter the port to
configure.
Block unknown multicast forwarding to the port.
Block unknown unicast flooding to the port.
Return to privileged EXEC mode.
Verify your entries, entering the appropriate command
once for the multicast option and once for the unicast
option.
Chapter 7 Configuring the Switch Ports
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