8.7.18 EN-DC Configuration Transfer

36.4233GPPEvolved Universal Terrestrial Radio Access Network (E-UTRAN)Release 17TSX2 Application Protocol (X2AP)

8.7.18.1 General

The purpose of the EN-DC Configuration Transfer procedure is to transfer the EN-DC SON Configuration container, either from the eNB to the en-gNB or from the en-gNB to the eNB, in the context of en-gNB X2 TNL address discovery as described in TS 36.300 [15].

The procedure uses non UE-associated signalling.

8.7.18.2 Successful Operation

Figure 8.7.18.2-1: eNB initiated EN-DC Configuration Transfer, successful operation

Figure 8.7.18.2-2: en-gNB initiated EN-DC Configuration Transfer, successful operation

The eNB initiates the procedure by sending the EN-DC CONFIGURATION TRANSFER message to an en-gNB.

If the en-gNB receives, in the EN-DC SON Configuration Transfer IE, the SON Information IE containing the SON Information Request IE, it may transfer back the requested information towards the eNB indicated in the Source eNB-ID IE of the EN-DC SON Configuration Transfer IE by initiating the EN-DC Configuration Transfer procedure.

If the en-gNB receives, in the EN-DC SON Configuration Transfer IE, the X2 TNL Configuration Info IE containing the eNB X2 Extended Transport Layer Addresses IE, it may use it as part of its ACL functionality configuration actions, if such ACL functionality is deployed.

In case the IP-Sec Transport Layer Address IE is present and the GTP Transport Layer Addresses IE within the eNB X2 Extended Transport Layer Addresses IE is not empty, GTP traffic is conveyed within an IP-Sec tunnel terminated at the IP-Sec tunnel end point given in by the IP-Sec Transport Layer Address IE.

In case the IP-Sec Transport Layer Address IE is not present, GTP traffic is terminated at the end points given by the list of addresses in eNB GTP Transport Layer Addresses IE within the eNB X2 Extended Transport Layer Addresses IE.

In case the eNB GTP Transport Layer Addresses IE is empty and the IP-Sec Transport Layer Address IE is present, SCTP traffic is conveyed within an IP-Sec tunnel terminated at the IP-Sec tunnel end point given in the IP-Sec Transport Layer Address IE, within the eNB X2 Extended Transport Layer Addresses IE.

If the en-gNB is configured to use one IPsec tunnel for EN-DC X2 traffic (IPsec star topology) then the traffic to the peer eNB shall be routed through this IPsec tunnel and the IP-Sec Transport Layer Address IE shall be ignored.

The en-gNB initiates the procedure by sending the EN-DC CONFIGURATION TRANSFER message to an eNB.

If case of network sharing with multiple cell ID broadcast with shared X2-C signalling transport, as specified in TS 36.300 [15], the EN-DC CONFIGURATION TRANSFER message shall contain the Interface Instance Indication IE to identify the corresponding interface instance.

8.7.18.3 Abnormal Conditions

Void.