Section: 4.3.15a.3 SIPTO at the Local Network with L-GW function collocated with the (H)eNB
Content: SIPTO at the Local Network is achieved using a Local GW (L-GW) function collocated with the (H)eNB and using the same procedures as described in clause 4.3.15, with the following additions: - The (H)eNB supporting the SIPTO at the Local Network function includes the Local GW address to the MME in every INITIAL UE MESSAGE and every UPLINK NAS TRANSPORT control message specified in TS 36.413[ Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP) ]  [36]. - The PDN GW selection function uses the L-GW address proposed by (H)eNB in the S1-AP message, instead of DNS interrogation. - Specific to the HeNB subsystem, the Local GW information for SIPTO at the Local Network is signalled on S1 separately from the Local GW information for LIPA. The L-GW shall be able to discriminate between PDN connection for SIPTO at the Local Network and for LIPA. NOTE 1: The protocol option (i.e. GTP or PMIP) supported on the S5 interface between Local GW and S-GW is configured on the MME. The direct user plane path between the (H)eNB and the collocated L-GW is enabled with a SIPTO Correlation ID parameter that is associated with the default EPS bearer on the PDN connection used for SIPTO at the Local Network. Upon establishment of the default EPS bearer the MME sets the SIPTO Correlation ID equal to the PDN GW TEID (GTP-based S5) or the PDN GW GRE key (PMIP-based S5). The SIPTO Correlation ID is then signalled by the MME to the (H)eNB as part of E-RAB establishment and is stored in the E-RAB context in the (H)eNB. The SIPTO Correlation ID is used in the (H)eNB for matching the radio bearers with the direct user plane path connections from the collocated L-GW for SIPTO at local network PDN connection. As IP data session continuity for the SIPTO at the Local Network PDN connection is not supported in this release of the specification, the SIPTO at the Local Network PDN connection shall be re-established when the UE moves away from (H)eNB. During the handover procedure, when the source (H)eNB releases its resources related to the UE, the (H)eNB shall request using intra-node signalling the collocated L-GW to re-establish the SIPTO at the Local Network PDN connection. The L-GW starts a timer. When the timer expires, the L-GW shall initiate the release of the SIPTO at the Local Network PDN connection using the PDN GW initiated bearer deactivation procedure according to clause 5.4.4.1 with the "reactivation requested" cause value.