Configuring an Interface for DHCPv6 Mode

DHCPv6 (DHCP for IPv6) is a client/server protocol that provides stateful address configuration or stateless configuration setting for IPv6 hosts. DHCPv6 client is enabled to learn IPv6 address and network parameters when the interface is configured to DHCPv6 mode.

DHCPv6 defines two different configuration modes:

• DHCPv6 stateful mode: DHCPv6 clients require IPv6 address together with other network parameters (for example, DNS Server, Domain Name).

• DHCPv6 stateless mode: DHCPv6 client only obtains network parameters other than IPv6 address.

Choosing mode depends on the Managed (M) Address Configuration and Other (O) Configuration flags in the advertised Router Advertisement message.

DHCPv6 infrastructure

Flag		Configuration
M	O
0	0	No DHCPv6 infrastructure.
1	1	IPv6 host uses DHCPv6 for both IPv6 address and other network parameter settings.
0	1	IPv6 host uses DHCPv6 only for IPv6 address assignment.
1	0	IPv6 host uses DHCPv6 only for other network parameter settings, known as DHCPv6 stateless.

There are three types of IPv6 addresses that can be assigned under DHCPv6:

• Automatic Address

• Autonomous Address

• IPv6 Address assigned through DHCPv6 client

To configure an interface for a DHCPv6 address

1. Navigate to Network > System > Interfaces > Interfaces Settings.

2. If you are configuring an unassigned interface, click IPv4.

3. Hover over an interface that you want to configure and click the Edit icon. The Edit Interface dialog box is displayed.

4. In the Zone drop-down menu, select WAN.

5. In the IP Assignment drop-down menu, select DHCP.

6. Click OK.

7. At the top, click IPv6. IPv6 addresses for the appliance are displayed.

8. Hover over an interface and click the Edit icon. The Edit Interface dialog box is displayed.

9. In the IP Assignment drop-down menu, select DHCPv6.

10. Turn on the Enable DHCPv6 prefix delegation toggle button, the following options become available.

    • Send preferred delegated prefix - Select this option to require a DHCAPv6 client to try to send the preferred delegated prefix specified in the two fields.

    • Send hints for renewing previous delegated prefix on startup - Select this option to require a DHCPv6 client to try to renew the delegated prefix assigned before when the firewall started up.

11. Use Rapid Commit Option - If enabled, DHCPv6 client uses message exchange for address assignment.

12. Send hints for renewing previous IP on startup - If enabled, DHCPv6 client tries to renew the address assigned before when firewall startup.

13. Select the DHCPv6 Mode for the interface. As required by RFC, DHCPv6 client depends on the Router Advertisement message to decide which mode (stateful or stateless) it should choose. This definition limits the user's choice to determine the DHCPv6 mode by itself. SonicWall’s implementation of DHCPv6 defines two different modes to balance the conformance and flexibility:

    • Automatic - The IPv6 interface configures IPv6 addresses using stateless/stateful autoconfiguration in accord with the M and O settings in the most recently received router advertisement message. See DHCPv6 Infrastructure.

    • Manual - The DHCPv6 mode is manually configured regardless of any received Router Advertisement.

    The Only Request Stateless Information option determines which DHCPv6 mode is used. If this option is unchecked, DHCPv6 client is under stateful mode; if it is checked, DHCPv6 client is under stateless mode and only obtains network parameters.

14. Turn on the Only Request Stateless Information toggle button to have DHCPv6 clients only request network parameter setting from the DHCPv6 server. The IPv6 address is assigned through stateless auto-configuration.

15. Optionally, you can configure Management login or User Login.

16. Optionally click the Advanced tab to configure Advanced options and/or click the Protocol tab to view DHCPv6 stateful and stateless configuration information.

17. Click OK.