Chapter 25 IP Source Guard

The following table describes the labels in this screen.

Table 68 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: If DHCP is enabled and there are no trusted ports,

 

DHCP requests will not succeed.

 

 

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 25.5.2 on page 231) 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

interval

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

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

Snooping URL

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 25.4 on page 225).

 

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GS2200-24 User’s Guide