Chapter 18 IP Source Guard
GS1510 Series User’s Guide
106
These MAC address filters are different than regular MAC address filters.
• They are stored only in volatile memory.
• They do not use the same space in memory that regular MAC address filters
use.
• They appear only in the ARP Inspection screens.
18.3.2.2 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.
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.
18.3.2.3 Syslog
The Switch can send syslog messages to the specified syslog server (Chapter 21
on page 133) 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.
18.3.2.4 Configuring ARP Inspection
Follow these steps to configure ARP inspection on the Switch.
1 Configure DHCP snooping. See Section 18.3.1.3 on page 105.
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.
