ZyXEL Communications GS1920v2 Series User Manual page 257

• It pretends to be computer
As a result, all the communication between computer
Computer
X
26.11.2.1 ARP Inspe c tio n a nd MAC Addre ss Filte rs
When the Switch 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 Switch.
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
and commands.
26.11.2.2 T ruste 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/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.
26.11.2.3 Syslo g
The Switch can send syslog messages to the specified syslog server
forwards or discards ARP packets. The Switch can consolidate log messages and send log messages in
batches to make this mechanism more efficient.
26.11.2.4 C o nfig uring ARP Inspe c tio n
Follow these steps to configure ARP inspection on the Switch.
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 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 26 IP Source Guard
and sends a message to computer
B
can read and alter the information passed between them.
ARP Inspe c tio n
Section 26.11.1.4 on page
GS1920v2 Series User's Guide
and computer
A
screens and commands, not in the
256.
257
.
A
passes through computer
B
(Chapter 12 on page
MAC Addre ss Filte r
(Chapter 43 on page 372) when it
.
X
133).
screens