l scope IPv6 address is created by combining a prefix obtained from Router Advertisement's PIO option, which has an autonomous 'A'-flag bit set, with an IID. A host may configure a multitude of IPv6 addresses from a single prefix, and in a case multiple prefixes are available, multiple addresses from different prefixes. Multitude of prefixes may be received via a single Router Advertisement or from multiple Router Advertisements received from multiple routers. The PIOs also contain valid lifetime and preferred lifetime information for each prefix, and these are used for advancing an address through the states listed above. Once a 'tentative' state global scoped address is created, the DAD procedure is started just as for link-local address. 3.5.2 Dynamic Host Configuration Protocol Version 6 In this section we will briefly introduce Stateful DHCPv6, as it is a significant part of IPv6 suite. 3GPP-based hosts very commonly support Ethernet-based interfaces, such as IEEE 802.11 Wireless Local Area Network (WLAN) networks, where Stateful Address Autoconfiguration is often used. In 3GPP networks, stateful DHCPv6 is not supported for configuring addresses for hosts' cellular interfaces. For a long time, only Stateless DHCPv6 was supported for parameter configuration, but since 3GPP Release-10, prefix delegation has been part of 3GPP specifications (see more in Section 4.4.6). Hence we will explain the DHCPv6 PD in more depth. While the DHCPv6 is an integral part of the IPv6 suite, it is running on top of UDP and hence could be considered to be an application layer protocol. The UDP ports used by the DHCPv6 are '547' for servers and relays, and '546' for clients. As with any UDP- based application, if the overall packet size exceeds the Path MTU, fragmentation and reassembly is required. To increase reliability and simplicity, DHCPv6 servers may try to keep message size under the minimum Path MTU of 1280 bytes. Stateful DHCPv6 According to the specifications, a host that supports a DHCPv6 client, initiates Stateful Add