ZyXEL Communications OLT2406 User Manual page 551

77.1.2.1 ARP Inspection and MAC Address Filters
When the OLT identifies an unauthorized ARP packet, it automatically creates a MAC address filter to
block traffic from the source MAC address and source VLAN ID of the unauthorized ARP packet. You
can configure how long the MAC address filter remains in the OLT.
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 commands, not in the MAC address Filter commands.
77.1.2.2 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
OLT receives ARP packets on untrusted ports.
The OLT does not discard ARP packets on trusted ports for any reason.
The OLT 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.
77.1.2.3 Syslog
The OLT can send syslog messages to the specified syslog server
forwards or discards ARP packets. The OLT can consolidate log messages and send log messages in
batches to make this mechanism more efficient.
77.1.2.4 Configuring ARP Inspection
Follow these steps to configure ARP inspection on the OLT.
Configure DHCP snooping. See
1
Note: It is recommended you enable DHCP snooping at least one day before you enable
ARP inspection so that the OLT 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 77 IP Source Guard
Section 77.1.1.4 on page
OLT2406 User's Guide
551
(Chapter 62 on page
(Chapter 87 on page
550.
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