7.7.81 Direct Tunnel Flags

29.0603GPPGeneral Packet Radio Service (GPRS)GPRS Tunnelling Protocol (GTP) across the Gn and Gp interfaceRelease 17TS

The Direct Tunnel Flags information element is used to hold values for multiple bit flags related to the GTP direct tunnel feature.

The Direct Tunnel Indicator (DTI) bit field is relevant only for the Update PDP Context procedure to indicate whether the procedure is being used for the establishment of a direct GTP-U tunnel between the GGSN and the RNC.

The GPRS-CSI (GCSI) bit field is relevant only for the SRNS Relocation procedure and Inter-RAT handover procedure and is used to indicate to the new SGSN whether the subscriber’s profile in the old SGSN contained a GCSI.

The Error Indication (EI) bit is relevant only for the case when a direct tunnel is used and the GGSN receives an Error Indication message from the RNC.

Bits marked as "Spare" shall be assigned the value 0 by the sending node and shall not be evaluated by the receiving node.

If a receiving entity receives this IE with a length longer than expected, it shall process the first octet(s) that are expected and shall silently discard the remaining octets.

					Bits
	Octets	8	7	6	5	4	3	2	1
	1	Type=182 (Decimal)
	2-3	Length
	4 – n	Spare	Spare	Spare	Spare	Spare	EI	GCSI	DTI

NOTE: In the present release of the present document, n=4 in the above figure. In future releases of the present document, n may be greater.

Figure 7.7.81.1: Direct Tunnel Flags Information Element