From the navigation tree, double-click Security.
In the Security tree, click DHCP Snooping.
In the work area, click the DHCP Snooping Globals tab.
In the DHCP Snooping External Save section, select the Enabled checkbox, to enable DHCP Snooping external save.
OR
In the DHCP Snooping External Save section, clear the Enabled checkbox, to disable DHCP Snooping external save.
Click a TftpServerAddressType button.
Type a value in the TftpServerAddress box.
Type a value in the UsbTargetUnit box.
Type a value in the Filename box.
To force a binding table restore, click the ForceRestore button.
On the toolbar, click Apply.