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Chapter 25 IP Source Guard

GS2200-8/24 User’s Guide

214

25.10.2.2 Trusted vs. Untrusted Ports

Every port is either a trusted port or an untrusted port for ARP inspection. This setting is

independent of the trusted/untrusted setting for DHCP snooping. You can also specify the maximum

rate at which the Switch receives ARP packets on untrusted ports.

The Switch does not discard ARP packets on trusted ports for any reason.

The Switch discards ARP packets on untrusted ports in the following situations:

• The sender’s information in the ARP packet does not match any of the current bindings.

• The rate at which ARP packets arrive is too high.

25.10.2.3 Syslog

The Switch can send syslog messages to the specified syslog server (Chapter 37 on page 287)

when it forwards or discards ARP packets. The Switch can consolidate log messages and send log

messages in batches to make this mechanism more efficient.

25.10.2.4 Configuring ARP Inspection

Follow these steps to configure ARP inspection on the Switch.

1 Configure DHCP snooping. See Section 25.10.1.4 on page 213.

Note: It is recommended you enable DHCP snooping at least one day before you enable

ARP inspection so that the Switch has enough time to build the binding table.

2 Enable ARP inspection on each VLAN.

3 Configure trusted and untrusted ports, and specify the maximum number of ARP packets that each

port can receive per second.