GS1920 Series User’s Guide
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C
H A P T E R
2 5
IP Source Guard
25.1
Overview
Use IP source guard to filter unauthorized DHCP and ARP packets in your network.
IP source guard uses a binding table to distinguish between authorized and unauthorized DHCP and
ARP packets in your network. A binding contains these key attributes:
•
MAC address
•
VLAN ID
•
IP address
•
Port number
When the Switch receives a DHCP or ARP packet, it looks up the appropriate MAC address, VLAN ID,
IP address, and port number in the binding table. If there is a binding, the Switch forwards the
packet. If there is not a binding, the Switch discards the packet.
25.1.1
What You Can Do
•
Use the IP Source Guard screen (Section 25.2 on page 201) to look at the current bindings for
DHCP snooping and ARP inspection.
•
Use the IP Source Guard Static Binding screen (Section 25.3 on page 202) to manage static
bindings for DHCP snooping and ARP inspection.
•
Use the DHCP Snooping screen (Section 25.4 on page 203) to look at various statistics about
the DHCP snooping database.
•
Use this DHCP Snooping Configure screen (Section 25.5 on page 206) to enable DHCP
snooping on the Switch (not on specific VLAN), specify the VLAN where the default DHCP server
is located, and configure the DHCP snooping database.
•
Use the DHCP Snooping Port Configure screen (Section 25.5.1 on page 208) to specify
whether ports are trusted or untrusted ports for DHCP snooping.
•
Use the DHCP VLAN Configure screen (Section 25.5.2 on page 210) to enable DHCP snooping
on each VLAN and to specify whether or not the Switch adds DHCP relay agent option 82
information to DHCP requests that the Switch relays to a DHCP server for each VLAN.
•
Use the DHCP Snooping VLAN Port Configure screen (Section 25.5.3 on page 210) to apply a
different DHCP option 82 profile to certain ports in a VLAN.
•
Use the ARP Inspection Status screen (Section 25.6 on page 212) to look at the current list of
MAC address filters that were created because the Switch identified an unauthorized ARP packet.
•
Use the ARP Inspection VLAN Status screen (Section 25.7 on page 213) to look at various
statistics about ARP packets in each VLAN.
•
Use the ARP Inspection Log Status screen (Section 25.8 on page 213) to look at log messages
that were generated by ARP packets and that have not been sent to the syslog server yet.
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