For quantum key distribution networks (QKDN), Recommendation ITU-T Y.QKDN_iwac specifies functional architecture models for QKDN interworking (QKDNi), i.e., functional architecture with GateWay Nodes (GWNs) and functional architecture with InterWorking Nodes (IWNs). In order realize these two models, it specifies detailed functional elements, basic operational procedures, and architectural configurations for QKDNi.