Section: 8.17.1 IAB Inter-donor-DU Re-routing
Content: When an IAB-donor-DU is configured to support inter-donor-DU re-routing, the IAB-donor-DU may identify a re-routed UL IP packet based on the source IP address field of the UL packet, and forwards UL IP packets, whose source IP addresses are anchored at a peer IAB-donor-DU, to this peer IAB-donor-DU via a tunnel. The IAB-donor-DU and the peer IAB-donor-DU may be controlled by the same IAB-donor-CU or by two different IAB-donor-CUs. The inter-donor-DU tunnel may be a GTP-U tunnel. The configuration of the tunnel is up to implementation. At the IAB-donor-DU forwarding the UL IP packets, inter-donor-DU tunnelling may be restricted to only a subset of the IP addresses anchored at the peer IAB-donor-DU. For this purpose, the IAB-donor-CU configures the IAB-donor-DU for forwarding the UL IP packets with a list of TNL addresses and/or prefixes for which tunnelling should be permitted and TNL address filtering should be exempted. NOTE: Tunnel types other than GTP-U may be used for the inter-donor-DU tunnel, by implementation.