Chapter 25 IP Source Guard
GS1920 Series User’s Guide
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•
Use the ARP Inspection Configure screen (Section 25.9 on page 215) to enable ARP inspection
on the Switch. You can also configure the length of time the Switch stores records of discarded
ARP packets and global settings for the ARP inspection log.
•
Use the ARP Inspection Port Configure screen (Section 25.9.1 on page 216) to specify
whether ports are trusted or untrusted ports for ARP inspection.
•
Use the ARP Inspection VLAN Configure screen (Section 25.9.2 on page 218) to enable ARP
inspection on each VLAN and to specify when the Switch generates log messages for receiving
ARP packets from each VLAN.
25.1.2
What You Need to Know
The Switch builds the binding table by snooping DHCP packets (dynamic bindings) and from
information provided manually by administrators (static bindings).
IP source guard consists of the following features:
•
Static bindings. Use this to create static bindings in the binding table.
•
DHCP snooping. Use this to filter unauthorized DHCP packets on the network and to build the
binding table dynamically.
•
ARP inspection. Use this to filter unauthorized ARP packets on the network.
If you want to use dynamic bindings to filter unauthorized ARP packets (typical implementation),
you have to enable DHCP snooping before you enable ARP inspection.
25.2
IP Source Guard
Use this screen to look at the current bindings for DHCP snooping and ARP inspection. Bindings are
used by DHCP snooping and ARP inspection to distinguish between authorized and unauthorized
packets in the network. The Switch learns the bindings by snooping DHCP packets (dynamic
bindings) and from information provided manually by administrators (static bindings).
To open this
screen, click Advanced Application > IP Source Guard.
Figure 146
Advanced Application > IP Source Guard
The following table describes the labels in this screen.
Table 89
Advanced Application > IP Source Guard
LABEL
DESCRIPTION
Index
This field displays a sequential number for each binding.
MAC Address
This field displays the source MAC address in the binding.
IP Address
This field displays the IP address assigned to the MAC address in the binding.
Lease
This field displays how many days, hours, minutes, and seconds the binding is valid; for
example, 2d3h4m5s means the binding is still valid for 2 days, 3 hours, 4 minutes, and
5 seconds. This field displays infinity if the binding is always valid (for example, a static
binding).
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