Security: IPv6 First Hop Security
Configuring IPv6 First Hop Security through Web GUI
557 Cisco Sx350, SG350X, SG350XG, Sx550X & SG550XG Series Managed Switches, Firmware Release 2.2.5.x
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STEP  4 To configure system-defined default policies or existing user defined policy select the policy 
in the policy table and click Edit.
STEP  5 To attach this policy to an interface:
• Attach Policy to VLAN—Click to jump to Policy Attachment (VLAN) page where 
you can attach this policy to a VLAN.
• Attach Policy to Interface—Click to jump to Policy Attachment (Port) page where you 
can attach this policy to a port.
DHCPv6 Guard Settings
Use the DHCPv6 Guard Settings page to enable the DHCPv6 Guard feature on a specified 
group of VLANs and to set the global configuration values for this feature. If required, a 
policy can be added or the system-defined default DHCPv6 Guard policies can be configured 
in this page.
To configure DHCPv6 Guard: 
STEP 1 Click Security > IPv6 First Hop Security > DHCPv6 Guard Settings. 
The currently-defined polices are displayed. For each policy, its Policy Type is displayed, 
which indicates whether it is a default or user-defined policy.
STEP  2 Enter the following global configuration fields:
• DHCPv6 Guard VLAN List—Enter one or more VLANs on which DHCPv6 Guard is 
enabled.
• Device Role—Displays the device role. See definition in the Add page.
• Minimal Preference—This field indicates whether the DHCPv6 Guard policy will 
check the minimum advertised preference value of the packet received.
- No Verification—Disables verification of the minimum advertised preference value 
of the packet received.
- User Defined—Verifies that the advertised preference value is greater than or equal 
to this value. This value must be less than the Maximal Preference value.
• Maximal Preference—This field indicates whether the DHCPv6 Guard policy will 
check the maximum advertised preference value of the packet received. This value must 
be greater than the Minimal Preference value.
- No Verification—Disables verification of the lower boundary of the hop count limit.