Chapter 28 ARP Inspection
GS2220 Series User’s Guide
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• They appear only in the ARP Inspe c tio n screens and commands, not in the MAC Addre ss Filte r screens
and commands.
28.11.1.2 Truste d vs. Untruste d Po rts
Every port is either a trusted port or an untrusted port for ARP inspection. This setting is independent of
the trusted or 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.
28.11.1.3 Syslo g
The Switch can send syslog messages to the specified syslog server 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.
28.11.1.4 Config uring ARP Inspe c tio n
Follow these steps to configure ARP inspection on the Switch.
1 Configure DHCP snooping.
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.
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