ns of IAB nodes. The configurations of BAP routing IDs and routing table entries is performed using a new class 1 F1-AP procedure defined for that purpose, called BH ROUTING CONFIGURATION The IP layer on top of the BAP layer enables IP routability between IAB node and IAB donor CU across wireless and wireline networks. Since the IP layer is primarily used to carry F1 protocols, it has been logically associated with the IAB donor DU. This sets it apart from the IAB node MT's IP connectivity to a data network, which is provided via a PDU 5.2 Wireless Relaying in 5G session (for IAB nodes using standalone 5GC mode) or PDN connection (for IAB nodes using EN-DC). The IAB node DU's IP address is different from that allocated to the collo- cated IAB node MT since they connect to different IP networks. While the IAB node MT's IP address is configured by the core network using Uu procedures, the IAB node DU's IP address is allocated within RAN by the IAB donor. In case the IAB donor is split, the IAB donor DU holds an IP router function, which interconnects wireless and wireline IP networks. For IP packets arriving from the wireline network (downstream direction), the IAB donor DU inserts the BAP header and selects the backhaul link as well as RLC channel. For this purpose, it needs to hold a mapping between IP packet header information and L2 parameters (i.e. BAP routing ID and RLC channel ID). It is not possible to use inner packet headers for this mapping since they are protected via a security layer such as IPsec. For this mapping, a combination of destination IP address, Differentiated Services Code Point (DSCP) field, and Flow Label field for IPv6 are used to indicate BAP routing ID and RLC channel ID. The mapping rules are configured by the IAB donor CU on the IAB donor DU via F1-C. In the case where the IAB donor CU is split into control-plane and user-plane parts, the CU-CP has to configure the selection of the corresponding IP header field values (e.g. such as Flow Label values) on the CU-UP via the E1 interface