ZyXEL Communications XGS-4526 User Manual
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Chapter 26 IP Source Guard
XGS-4526 User’s Guide
252
The following table describes the labels in this screen.
Table 79 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 (
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 (