ugust 2010. 161. Savola, P. and Haberman, B. Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address. RFC 3956, Internet Engineering Task Force, November 2004. 162. Perkins, C. IP Mobility Support for IPv4, Revised. RFC 5944, Internet Engineering Task Force, November 2010. IPv6 in 3GPP Networks This chapter introduces how Internet Protocol version 6 (IPv6) is implemented in 3rd Generation Partnership Project (3GPP) core networks and 3GPP compliant User Equip- ments (UEs). We will also take a look into network aspects that are specific to 3GPP. The network architectures of interest are the General Packet Radio Service (GPRS) and the Evolved Packet System (EPS), which both provide packet switched services. For read- ability reasons we will primarily use the terminology of the EPS, unless specifically noted when some technical aspect is particular to the GPRS. 4.1 PDN Connectivity Service One of the basic concepts in 3GPP network architecture is the Packet Data Network (PDN) Connectivity Service, which offers Internet Protocol (IP) connectivity and services between the User Equipment (UE) and the Public Land Mobile Network (PLMN) external IP-based PDN network. The PDN Connectivity Service supports the transport of IP flow aggregates, consisting of one or more flows identified by various IP flow filters. The PDN can be an internal, walled-garden-like IP network within the mobile operator network, any IP network outside operator administration, such as the Internet. PDN Connectivity is realized as an established PDN Connection. PDN Connection is the association between a UE and a PDN represented by an Access Point Name (APN). Each PDN Connection has an associated Internet Protocol version 4 (IPv4) address [1] and/or an IPv6 prefix [2]. This section describes the PDN Connectivity Services aspects that matter, from the IPv6 usage and deployment point of view. For simplicity we use the term packet core to mean both the GPRS and the Evolved Packet Core (EPC), unless otherwise stated. The selection of a de