PD-Mode

Mobile/cellular networks that support IPv6 only support DHCPv6 prefix delegation as of 3GPP Release 10. Consequently, a terminal device in a mobile network older than Release 10 can only be assigned one /64 prefix, for example by means of router advertisements. IPv6 support is easy to implement for smartphones or laptops using this method. However, an IPv6 router needs at least one more prefix that it can propagate to clients on the LAN.

IPv6 prefix delegation from the WWAN to the LAN allows clients to work on the LAN with a /64 prefix that is assigned from the WAN. A consequence of this is that a router is able to operate in an IPv6 cellular network without DHCPv6 prefix delegation and neighbor discovery proxy (ND proxy). The router announces the retrieved /64 prefix on the LAN by router advertisement, instead of adding it at the WAN interface. Clients generate an address from this prefix and use it for their IPv6 communications.