Cisco Systems IC-23 Enabling Source Address Control, Enabling SNMP Illegal Address Trap, IC-46

Configuring LAN Interfaces

Configuring a Hub Interface

To enable the link test function on a hub port connected to an Ethernet interface, use the following command in hub configuration mode:

Command

link-test

Purpose

Enables the link test function.

Enabling Source Address Control

On an Ethernet hub port only, you can configure a security measure such that the port accepts packets only from a specific MAC address. For example, suppose your workstation is connected to port 3 on a hub, and source address control is enabled on port 3. Your workstation has access to the network because the hub accepts any packet from port 3 with your workstation’s MAC address. Any packets arriving with a different MAC address cause the port to be disabled. The port is enabled again after 1 minute and the MAC address of incoming packets is checked again.

To enable source address control on a per-port basis, use the following command in hub configuration mode:

Command	Purpose
source-address [mac-address]	Enables source address control.

If you omit the optional MAC address, the hub remembers the first MAC address it receives on the selected port, and allows only packets from the learned MAC address.

See the examples of establishing source address control in the “Hub Configuration Examples” section.

Enabling SNMP Illegal Address Trap

To enable the router to issue an SNMP trap when an illegal MAC address is detected on an Ethernet hub port, use the following commands in hub configuration mode:

	Command	Purpose
Step 1
	hub ethernet number port [end-port]	Specifies the hub number and the hub port (or range of hub ports) and
		enters hub configuration mode.
Step 2
	snmp trap illegal-address	Enables the router to issue an SNMP trap when an illegal MAC address
		is detected on the hub port.

You may need to set up a host receiver for this trap type (snmp-server host) for a Network Management System (NMS) to receive this trap type. The default is no trap. For an example of configuring a SNMP trap for an Ethernet hub port, see the “Hub Configuration Examples” section.

Cisco IOS Interface Configuration Guide

IC-46