ZyXEL Communications XGS2220 Series User Manual page 517

• They appear only in the ARP Inspection screens and commands, not in the MAC Address Filter screens
and commands.
75.15.1.2 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 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.
75.15.1.3 Syslog
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.
75.15.1.4 Configuring ARP Inspection
Follow these steps to configure ARP inspection on the Switch.
Configure DHCP snooping.
1
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.
Enable ARP inspection on each VLAN.
2
Configure trusted and untrusted ports, and specify the maximum number of ARP packets that each port
3
can receive per second.
Chapter 75 ARP Inspection
XGS2220 Series User's Guide
517