Chapter 26 IP Source Guard

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

Enter how long (10-65535 seconds) the Switch tries to complete a

interval

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

interval

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

Enter the location of a DHCP snooping database, and click Renew if

Snooping URL

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.

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XGS-4526/4528F/4728F User’s Guide