Switchport Block - Cisco ME 3400 Command Reference Manual

Ethernet access switch

Hide thumbs Also See for ME 3400:

Table of Contents

switchport block

Use the switchport block interface configuration command to prevent unknown multicast or unicast

packets from being forwarded. Use the no form of this command to allow forwarding unknown multicast

or unicast packets.

Syntax Description

Unknown multicast and unicast traffic is not blocked.

Command Modes

Interface configuration

Command History

Usage Guidelines

By default, all traffic with unknown MAC addresses is sent to all ports. You can block unknown multicast

or unicast traffic on protected or nonprotected ports. If unknown multicast or unicast traffic is not

blocked on a protected port, there could be security issues.

With multicast traffic, the port blocking feature blocks only pure Layer 2 packets. Multicast packets that

contain IPv4 or IPv6 information in the header are not blocked.

If the port is a user network interface (UNI) or enhanced network interface (ENI), you must use the no

shutdown interface configuration command to enable it before using the switchport block command.

UNIs and ENIs are disabled by default. Network node interfaces (NNIs) are enabled by default.

Blocking unknown multicast or unicast traffic is not automatically enabled on protected ports; you must

explicitly configure it.

For more information about blocking packets, see the software configuration guide for this release.

This example shows how to block unknown multicast traffic on an interface:

Switch(config-if)# switchport block multicast

You can verify your setting by entering the show interfaces interface-id switchport privileged EXEC

Cisco ME 3400 Ethernet Access Switch Command Reference

switchport block {multicast | unicast}

no switchport block {multicast | unicast}

Specify that unknown multicast traffic should be blocked.

Specify that unknown unicast traffic should be blocked.

Modification

This command was introduced.

Chapter 2 Cisco ME 3400 Ethernet Access Switch Cisco IOS Commands

Only pure Layer 2 multicast traffic is blocked. Multicast packets that

contain IPv4 or IPv6 information in the header are not blocked.