ZyXEL ES-3148 Guida Utente

 Chapter 24 IP Source Guard

ES-3148 User’s Guide

Use this screen to specify whether ports are trusted or untrusted ports for DHCP snooping. 

"

The Switch will drop all DHCP requests if you enable DHCP snooping and 
there are no trusted ports.

You can also specify the maximum number for DHCP packets that each port (trusted or 
untrusted) can receive each second. To open this screen, click Advanced Application > IP 
Source Guard > DHCP Snooping > Configure > Port.

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 

(

).

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.

Table 74   Advanced Application > IP Source Guard > DHCP Snooping > Configure