8.12 SRNS Data Forwarding Initiation

25.4133GPPRelease 17TSUTRAN Iu interface Radio Access Network Application Part (RANAP) signalling

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

8.12.1 General

The purpose of the SRNS Data Forwarding procedure is to trigger the transfer of N-PDUs from the RNC to the CN (PS domain) in case of intersystem change or in some further cases described in TS 23.060 [21]. The procedure uses connection oriented signalling.

8.12.2 Successful Operation

Figure 13: SRNS Data Forwarding Initiation procedure. Successful operation.

The CN initiates the procedure by sending an SRNS DATA FORWARD COMMAND message to the UTRAN. The SRNS DATA FORWARD COMMAND message includes the list of RABs towards the PS domain whose data should be forwarded, and the necessary information for establishing a GTP tunnel to be used for data forwarding. For each indicated RAB, the list shall include the RAB ID IE, the Transport Layer Address IE and the Iu Transport Association IE.

Upon reception of the SRNS DATA FORWARD COMMAND message the RNC starts the timer T_DATAfwd.

8.12.3 Abnormal Conditions

Not applicable.