Guidance to Readers of this Specification

In order to reduce the number of procedures in this specification certain editorial practices have been adopted. Though there are many independent factors, such as variants of S5/S8/S2b and attachment cases, these are in essence quite similar. So, rather than presenting the permutations of these factors separately and thereby needlessly repeating normative text, conventions have been adopted to combine this information in single procedures.

The S5 and S8 reference points in the EPC architecture have been defined to have both a GTP and PMIP variant. The GTP variant is documented in TS 23.401 [4], while the PMIP variant is documented in this specification. Every effort has been made to eliminate duplication of normative text common to both specifications. Many figures in this specification refer to procedures in TS 23.401 [4] to achieve this end. Common procedures between TS 23.401 [4] and TS 23.402 (this specification), are represented in this specification in figures by text in shaded box(es) that reference the appropriate figure and steps in TS 23.401 [4]. The details of the common steps are only captured in TS 23.401 [4].

The S2b reference point in the EPC architecture has also been defined to have both a GTP and PMIP variant. Both variants are documented in this specification. Every effort has been made to eliminate duplication of normative text common to both variants. Figures for the GTP variant of S2b refer to figures defined for the PMIP variant of S2b to achieve this end. Common procedures for both variants are represented in figures for GTP based S2b by text in shaded box(es) that reference the appropriate figure and steps defined for PMIP based S2b. The details of the common steps are only captured for the PMIP variant of S2b.

Attachment cases (as discussed in clauses 6.2.1 and 7.2.1) have been combined in a single figure. The different attachment cases can be accommodated by including optional items in the flows, for instance, a vPCRF that is only employed during when a roaming case or LBO is specified.

Multiple APN interactions may occur for many of the procedures defined in this specification. These interactions complicate the flows by introducing certain operations that may occur multiple times. Rather than produce unique flows for this purpose, we indicate where this possibility may occur in text.