Chapter 24 IP Source Guard
The following table describes the labels in this screen.
Table 73 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 24.5.2 on page 220) 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 |
| a specific update in the DHCP snooping database before it gives |
| up. |
|
|
Write delay | Enter how long |
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 |
Snooping URL | 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 24.4 on page 213). |
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