Section: 4.3.15a Selected IP Traffic Offload (SIPTO) at the Local Network 4.3.15a.1 General
Content: The SIPTO at the Local Network function enables an IP capable UE connected via a (H)eNB to access a defined IP network (e.g. the Internet) without the user plane traversing the mobile operator's network. The subscription data in the HSS are configured per user and per APN to indicate to the MME if offload at the local network is allowed or not. SIPTO at the Local Network can be achieved by selecting a L-GW function collocated with the (H)eNB or selecting stand-alone GWs (with S-GW and L-GW collocated) residing in the Local Network. In both cases the selected IP traffic is offloaded via the Local Network. Specific to the HeNB subsystem, the applicability of SIPTO at the Local Network does not depend on CSG membership and the feature can be applied to any UE, as long as the UE is allowed to access the cell. For this release of the specification, no interface between the L-GW and the PCRF is specified and there is no support for dedicated bearers on the PDN connection used for SIPTO at the Local Network. The Local GW (L-GW) shall reject any UE requested bearer resource modification. For this release of the specification, SIPTO at the Local Network is intended for offloading Internet traffic only, thus the L-GW does not provide APN specific connectivity. Therefore if the subscription data in the HSS indicate that offload at the Local Network is allowed, this implies that the related APN is typically used for providing Internet connectivity. If the MME detects a change in SIPTO permissions in the subscription data for a given subscriber for a given APN and the subscriber has already established a SIPTO at the local network PDN connection to that APN, the MME shall release the SIPTO at the Local Network PDN connection for that APN with "reactivation requested" cause as specified in clause 5.10.3. NOTE: In this release of the specification it is assumed that the target S-GW selected during the Handover also has connectivity to the L-GW.