Disabling Storm Control; Blocking Flooded Traffic On A Port; Resuming Normal Forwarding On A Port - Cisco WS-C2955T-12 Software Manual

Chapter 7 Configuring the Switch Ports

Disabling Storm Control

Beginning in privileged EXEC mode, follow these steps to disable broadcast-storm control:
Command
Step 1
configure terminal
Step 2 interface interface
Step 3
no port storm-control broadcast
Step 4
end
Step 5
show port storm-control [interface]

Blocking Flooded Traffic on a Port

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:
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

Resuming Normal Forwarding on a Port

Beginning in privileged EXEC mode, follow these steps to resume normal forwarding on a port:
Command
Step 1 configure terminal
Step 2
interface interface
Step 3
no port block multicast
Step 4 no port block unicast
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Purpose
Enter global configuration mode.
Enter interface configuration mode, and enter the port to configure.
Disable port storm control.
Return to privileged EXEC mode.
Verify your entries.
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.
Purpose
Enter global configuration mode.
Enter interface configuration mode, and enter the port to configure.
Enable unknown multicast forwarding to the port.
Enable unknown unicast flooding to the port.
Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide
Configuring Flooding Controls
7-5