Effective bandwidth utilization and scalability are vital issues for IP networking over a large-scale uni-directional link (UDL), such as a wide-area wireless broadcast over satellite or terrestrial digital broadcasting. On a large-scale UDL, the current network architecture is not scalable to cover an extraordinary number of receivers that communicate using a Link-layer Tunneling Mechanism (LLTM). This paper proposes a network architecture for a large-scale UDL that: (1) decreases the traffic load of LLTM at the upstream network of the UDL, (2) coordinates the data link layer and network layer of receivers without communications via UDL, and (3) enables neighbor discovery for direct communication between receivers via a bi-directional link that is used as a return path for LLTM. Simulation results showed that our approach reduces by more than 90% the control messages to be sent via UDL compared with IPv6 stateless address autoconfiguration on the existing network architecture. Our proposal improves the UDL bandwidth consumption from O(N) to O(1), so that the bulk of the bandwidth can be utilized for delivering services, not for network configuration of receivers. © 2010 Information Processing Society of Japan.