Section: 11.2.1.3.5 IPv6 Prefix Delegation via DHCPv6
Content: Optionally, a single network prefix shorter than the default /64 prefix may be assigned to a PDN connection. In this case, the /64 default prefix used for IPv6 stateless autoconfiguration will be allocated from this network prefix; the remaining address space from the network prefix can be delegated to the PDN connection using prefix delegation after the PDP context activation/default bearer establishment and IPv6 prefix allocation via IPv6 stateless address autoconfiguration as defined in clause 11.2.1.3.2/11.2.1.3.2a. When PLMN based parameter configuration is used, the GGSN / PDN GW provides the requested IPv6 prefix from a locally provisioned pool. When external PDN based IPv6 prefix allocation is used, the GGSN / PDN GW may obtain the prefix from the external PDN as per subclauses 16.4 and 16a.4. For the detailed description of the UE uses DHCPv6 to request additional IPv6 prefixes refer to 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [3] and 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [77].