Content for  TS 23.060  Word version:  18.0.0

Modification procedures modify parameters that were negotiated during an activation procedure for one or several PDP contexts. An MS, a GGSN, a P-GW, an SGSN, a PCRF, or an RNC can request or initiate a modification procedure. The Modification procedures may possibly be triggered by the HLR as explained in clause "Insert Subscriber Data Procedure" or by an RNC in a RAB Release or an RNC-initiated RAB Modification procedure. An MS and SGSN can also decide about modification procedures after an RNC-initiated Iu release. The following parameters can be modified:

• QoS Negotiated;
• Negotiated Evolved ARP;
• Radio Priority;
• Packet Flow Id;
• PDP Address (in case of the GGSN-initiated modification procedure);
• TFT (in case of MS- or GGSN or PDN-GW-initiated modification procedure);
• Protocol Configuration Options (in case of MS and GGSN-initiated modification procedure);
• BCM (in case of GGSN-initiated or PDN-GW-initiated modification procedure);
• Usage of Direct Tunnel;
• APN-AMBR; and
• indication for one or more 3GPP RATs of whether the PDP context can be offloaded to WLAN.

The SGSN can request the modification of parameters by sending a Modify PDP Context Request message to the MS. A GGSN can request the modification of parameters by sending an Update PDP Context Request message to the SGSN. A P-GW can request the modification of parameters by sending an Update Bearer Request message to the S-GW. An MS can request the modification of parameters by sending a Modify PDP Context Request message to the SGSN. An RNC can request an Iu release by sending an Iu Release Request message to the SGSN. After Iu release the MS and SGSN shall modify the PDP contexts according to the rules defined in clause "RNC-Initiated PDP Context Modification Procedure". An RNC can request the release of a radio access bearer. After RAB release the MS and the SGSN shall locally modify the corresponding PDP context according to rules defined in the clause "RAB Release-Initiated Local PDP Context Modification Procedure". A trace may be activated while a PDP context is active. To enable trace activation in a GGSN, the SGSN shall send an Update PDP Context Request message to the GGSN. To enable trace activation in a P-GW, the SGSN shall send an Update Bearer Request message to the S-GW. If PDP context modification is performed only to activate a trace, the SGSN shall not send a Modify PDP Context Request message to the MS. When the APN restriction value configured in the GGSN/P-GW is modified, the GGSN/P-GW applies the new APN restriction value to new PDP contexts/EPS bearers. Existing PDP contexts/EPS bearers continue to use the previous APN restriction value. If the GGSN has stored information that the current SGSN supports the reporting of CGI/SAI/RAI and/or user CSG information changes, to enable or disable CGI/SAI/RAI and/or user CSG information change reporting for an already active PDP context, the GGSN shall send an Update PDP Context Request message to the SGSN. The SGSN shall behave according to clause 15.1.1a. If the P-GW has stored information that the current S4-SGSN supports the reporting of CGI/SAI/RAI and/or user CSG information changes, to enable or disable CGI/SAI/RAI and/or user CSG information change reporting for an already active EPS Bearer, the P-GW shall send an Update Bearer Request message to the S-GW. The S4-SGSN shall behave according to clause 15.1.1a. An RNC may request the modification of some negotiated RAB related QoS parameters by sending a RAB Modify Request. For S4-based SGSNs the SGSN-Initiated PDP Context Modification can be used in the following use case:

• HSS initiated subscribed QoS modification, where typically QoS related parameters are changed. The parameters that may be modified are EPS Bearer QoS of the default bearer and APN-AMBR.
• A handover or RAU from Gn/Gp SGSN to S4-SGSN, if the S4-SGSN detects that the mapped EPS subscribed QoS profile (i.e. the subscribed QoS profile mapped according to TS 23.401, Annex E) of the default bearer is different from the EPS Subscribed QoS profile received from the HSS.

The SGSN-Initiated PDP Context Modification procedure is illustrated in Figures 70a and 70b.

If an APN Restriction is received from the GGSN for this PDP Context, then the SGSN shall store this value for the PDP Context, replacing any previously stored value for this PDP context. The SGSN shall determine a (new) value for the Maximum APN Restriction using any stored APN Restriction and the received APN Restriction. The GGSN may interact with PCRF (refer to TS 23.203, e.g. to deliver User Location Information and/or UE Time Zone Information if it was requested by the PRCF. The CAMEL procedure calls shall be performed, see referenced procedure in TS 23.078: The procedure returns as result "Continue".

The procedure described in Figure 70c shows only the steps, due to use of S4, that are different from the Gn/Gp variant of the procedures given by clause 9.2.3.1.

The procedure described in Figure 70d shows only the steps, due to use of S4, which are different from the Gn/Gp variant of the procedures given by clause 9.2.3.1.