ZyXEL Communications ES3500 Series VLAN, Active, Database, interval, DHCP Vlan, Agent URL, current one, Write delay, specific VLAN, ; for example, different VLAN, no trusted ports

Chapter 26 IP Source Guard

still available after a restart. To open this screen, click Advanced Application > IP Source Guard > DHCP Snooping > Configure.

Figure 120 DHCP Snooping Configure

The following table describes the labels in this screen.

Table 84 DHCP Snooping Configure

LABEL	DESCRIPTION
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 (Section
	26.5.2 on page 226) 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.
Database	If Timeout interval is greater than Write delay interval, it is possible that the next
	update is scheduled to occur before the current update has finished successfully or
	timed out. In this case, the Switch waits to start the next update until it completes the
	current one.
Agent URL	Enter the location of the DHCP snooping database. The location should be expressed
	like this: tftp://{domain name or IP address}/directory, if applicable/file
	name; for example, tftp://192.168.10.1/database.txt.
Timeout interval	Enter how long (10-65535 seconds) the Switch tries to complete a specific update in
	the DHCP snooping database before it gives up.
Write delay	Enter how long (10-65535 seconds) the Switch waits to update the DHCP snooping
interval	database the first time the current bindings change after an update. Once the next
	update is scheduled, additional changes in current bindings are automatically included
	in the next update.

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	ES3500 Series User’s Guide