Dhcp Snooping; Chapter 27 Dhcp Snooping; Dhcp Snooping Overview; What You Can Do - ZyXEL Communications 43222612 User Manual

27.1 DHCP Snooping Overview

With DHCP snooping, the Switch can build the binding table dynamically by snooping DHCP packets
(dynamic bindings) and filter unauthorized DHCP packets in your network.
The Switch uses a binding table to distinguish between authorized and unauthorized DHCP packets in
your network. A binding contains these key attributes:
• MAC address
• VLAN ID
• IP address
• Port number
When the Switch receives a DHCP 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.

27.1.1 What You Can Do

• Use the DHCP Snooping screen
snooping database.
• Use this DHCP Snooping Configure screen
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
are trusted or untrusted ports for DHCP snooping.
• Use the DHCP Snooping VLAN Configure screen
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
DHCP option 82 profile to certain ports in a VLAN.

DHCP Snooping

27.2
Use this screen to look at various statistics about the DHCP snooping database.
To open this screen, click Advanced Application > IP Source Guard > IPv4 Source Guard Setup > DHCP
Snooping.

Chapter 27 DHCP Snooping

C

DHCP Snooping

(Section 27.2 on page 263) to look at various statistics about the DHCP
(Section 27.3 on page
(Section 27.3.1 on page
(Section 27.3.2 on page
(Section 27.3.3 on page
GS2220 Series User's Guide
263
H A P T E R
266) to enable DHCP snooping on
267) to specify whether ports
268) to enable DHCP
269) to apply a different
27