Finding Feature Information - Cisco Catalyst 2960 series Configuration Manual

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and
feature information, see Bug Search Tool and the release notes for your platform and software release. To
find information about the features documented in this module, and to see a list of the releases in which each
feature is supported, see the feature information table at the end of this module.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not
required.
Information About Port Blocking
Port Blocking
By default, the switch floods packets with unknown destination MAC addresses out of all ports. If unknown
unicast and multicast traffic is forwarded to a protected port, there could be security issues. To prevent unknown
unicast or multicast traffic from being forwarded from one port to another, you can block a port (protected or
nonprotected) from flooding unknown unicast or multicast packets to other ports.
With multicast traffic, the port blocking feature blocks only pure Layer 2 packets. Multicast packets that
Note
contain IPv4 or IPv6 information in the header are not blocked.
How to Configure Port Blocking
Blocking Flooded Traffic on an Interface
Before You Begin
The interface can be a physical interface or an EtherChannel group. When you block multicast or unicast
traffic for a port channel, it is blocked on all ports in the port-channel group.
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
Finding Feature Information
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