ZyXEL Communications XGS-4528F, User Manual, Page: 270 / 491

Chapter 26 IP Source Guard
XGS-4526/4528F/4728F User’s Guide
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The following table describes the labels in this screen.
Table 80 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 272 ) 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
interval
Enter how long (10-65535 seconds) the Switch waits to update the
DHCP snooping 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.
Renew DHCP
Snooping URL
Enter the location of a DHCP snooping database, and click Renew if
you want the Switch to load it. You can use this to load dynamic
bindings from a different DHCP snooping database than the one
specified in Agent URL.
When the Switch loads dynamic bindings from a DHCP snooping
database, it does not discard the current dynamic bindings first. If
there is a conflict, the Switch keeps the dynamic binding in volatile
memory and updates the Binding collisions counter in the DHCP
Snooping screen (
Section 26.4 on page 266 ).
Apply Click Apply to save your changes to the Switch’s run-time memory.
The Switch loses these changes if it is turned off or loses power, so
use the Save link on the top navigation panel to save your changes to
the non-volatile memory when you are done configuring.
Cancel Click this to reset the values in this screen to their last-saved values.