ZyXEL ES-3148 Guida Utente

Chapter 24 IP Source Guard

ES-3148 User’s Guide

Use this screen 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. 
The DHCP snooping database stores the current bindings on a secure, external TFTP server so 
that they are still available after a restart. To open this screen, click Advanced Application > 
IP Source Guard > DHCP Snooping > Configure.

Figure 103   Advanced Application > IP Source Guard > DHCP Snooping > Configure

The following table describes the labels in this screen.

Table 74   Advanced Application > IP Source Guard > DHCP Snooping > Configure

Active

Select this to enable DHCP snooping on the Switch. You still have to 

enable DHCP snooping on specific VLAN and specify trusted ports.

Note: The Switch will drop all DHCP requests if you enable 

DHCP snooping and there are no trusted ports.

DHCP Vlan

Select a VLAN ID if you want the Switch to forward DHCP packets to 

DHCP servers on a specific VLAN.

Note: You have to enable DHCP snooping on the DHCP 

VLAN too.

You can enable Option82 in the DHCP Snooping VLAN Configure 

screen (

) to help the DHCP servers distinguish 

between DHCP requests from different VLAN.
Select Disable if you do not want the Switch to forward DHCP packets to a 

specific VLAN.