Section: 11.3 Numbering and Addressing
Content: In the case of interworking with public IP networks (such as the Internet), the PLMN operator shall use public network addresses. These public addresses can be reserved from the responsible IP numbering body, or from an ISP with which the PLMN operator has an agreement. In case of IPv6, a global IPv6 prefix can be obtained from the same sources. In the case of interworking with private IP networks, two scenarios can be identified: 1. the PLMN operator manages internally the subnetwork IPv4 addresses and/ or IPv6 prefixes as applicable. Each private network is assigned a unique subnetwork IPv4 addresses and/ or IPv6 prefixes. Normal routing functions are used to route packets to the appropriate private network; 2. each private network manages its own addressing. In general this will result in different private networks having overlapping address ranges. A logically separate connection (e.g. an IP in IP tunnel or layer 2 virtual circuit) is used between the GGSN/P-GW and each private network. In this case the IP address alone is not necessarily unique. The pair of values, Access Point Name (APN) and IPv4 address and/or IPv6 prefixes, is unique. NOTE 1: In IPv6, "site-local addresses"were originally designed to be used for addressing inside of a site that is similar to the usage of "private addresses" in IPv4. The usage of "site-local-addresses" is deprecated as specified in RFC 4291 [82]. Existing implementations and deployments may continue using site-local addresses. However, in new implementations the prefix that was allocated for "site local addresses" shall be treated as for "global unicast addresses", see RFC 4291 [82]. The PLMN operator allocates the IP addresses for the subscribers in either of the following ways. - The PLMN operator allocates a static IPv4 address and/or a static IPv6 prefix when the subscription record is built. The IPv4 address and/or IPv6 prefix are respectively reserved from a pool of free IPv4 addresses and/or IPv6 prefixes. Each external network has its own pool of IPv4 addresses and/or IPv6 prefixes. - The PLMN operator allocates (either on its own or in conjunction with the external network) a dynamic IPv4 address and/or a dynamic IPv6 prefix as described in 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [3], 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [77] and 3GPP TS 23.402[ Architecture enhancements for non-3GPP accesses ]  [78]. For UEs used for Machine-Type Communications (MTC) as described in 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [77] and 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [3] and Cellular Internet of Things (CIoT) as described in 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [77] and 3GPP TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [3], IPv6 address allocation should be the primary mechanism for IP address allocation. IPv4 based address allocation is considered a transition solution and is deprecated for MTC used over 3GPP accesses. NOTE 2: For implementation guidelines related to transition and other aspects of IPv4 address usage see 3GPP TS 23.221[ Architectural requirements ]  [99] Annex B. In case of transferring Non-IP data over SGi PtP tunnelling based on UDP/IP (see subclause 11.8) the PLMN operator uses private network addresses for the establishment of the tunnel.