tiple IAB nodes. The overall support of route redundancy remains limited since each IAB node can at most have two parent nodes. This restriction was made for Release-16 since it allowed the use of NR dual connectivity to reduce specification efforts. Another option proposed was to permit multiple MTs in each IAB node, which would remove this limitation. This feature may be added in later releases. Intial BAP route Additional BAP route Dual- Initial Initial path Additional Additional Additional Intial path IAB-donor connecting parent IAB- IAB-donor parent IAB- path IAB- path IAB- IAB-node IAB-node donorDU Downlink user data to UE Uplink user data from UE 1. Dual-connecting IAB-node MT establishes link to SCG on second parent DU using dual-connectivity procedure 2. IAB-donor CU configures backhaul connectivity via second parent node - Includes configuration of BH RLC channels, BAP and migrating IAB-node DU's IP address 3. Migration of F1 associations onto new backhaul route - Addition of new IP address as new TNLA for SCTP connection of F1-C Update IP address of F1-U tunnels Downlink user data to UE Uplink user data from UE Downlink user data to UE Uplink user data from UE Figure 5.2.13 Procedures for establishment of redundant route underneath same IAB donor. 5 NG-RAN Evolution Since IAB nodes may be deployed in urban areas with rather low antenna height the wireless backhaul may be vulnerable to changes in the propagation environment, for example, due to moving obstructions, changes in foliage, etc. IAB therefore supports a recovery mechanism in case backhaul radio link failure (RLF) occurs. For this purpose, the IAB node MT monitors the backhaul link. If the IAB node MT observes an RLF and has a redundant backhaul link, it informs the IAB donor CU about the event via a measurement report, which can switch all traffic to the alternative route. This applies to NR dual-connected IAB nodes. IAB nodes operating in EN-DC can use the LTE link to forward such measurement reports. If the IAB node MT is only single-connec