 issue can be introduced for UEs of later releases. IAB supports topological redundancy when an IAB node has multiple routes to an IAB donor. In Release-16, the IAB network is restricted to directed acyclic graph (DAG) topology, which imposes hierarchical structure and prohibits an IAB node from becoming a child and parent node of a peer at the same time. The IAB topology can be extended from spanning tree to DAG by allowing an IAB node to concurrently connect to multiple parent nodes. For this purpose, an IAB node can leverage the dual connectivity procedures (3GPP TS 38.300 clause 6.8), which allows an IAB node MT to establish independent links to an IAB donor CU via two parent node DUs. This solu- tion can only be applied for IAB nodes operating in standalone mode. IAB nodes operating in EN-DC already use one of the two links for LTE. Figure 5.2.13 shows the procedure for the establishment of a redundant route using dual connectivity. This procedure is shown for the same topology as in Figure 5.2.12a. The fol- lowing steps are included in this procedure: 1. The IAB node MT establishes a link to a second parent node. a. Via NR DC procedures (3GPP TS 38.300 clause 6.8), a secondary cell group is estab- lished on the second parent IAB node DU. As part of these procedures, a second RRC connection is established between the IAB node MT and the IAB donor CU via the second parent IAB node. 2. The IAB donor CU configures backhaul connectivity via the second parent node. 3. F1 connectivity is adapted to the additional backhaul route. a. For F1-C, the new IP address can be added as an alternative SCTP connection. b. Each F1-U can only use one IP address at a time. It is possible, however, to load- balance traffic by distributing F1-U tunnels to different routes, or to establish two F1-Us for each bearer. Route redundancy can be extended to descendant IAB nodes by adding BAP route and IP connectivity to these nodes via the second parent node. The degree of redundancy can be increased by adding a second parent link to mul