Scenarios related to 5G and beyond give rise to a high degree of heterogeneity in terms of applications, services, and user expectations as well as more demanding QoS require- ments with an end-to-end scope that can cover multiple operator domains. In this work, we design an inter-domain component that addresses the control plane challenges of establishing such end-to-end connectivity in a scalable, efficient, and automated way. Furthermore, we provide insights into operational aspects by investigating to which extent different traffic aggregation mechanisms can be used to benefit from economies of scale while meeting QoS constraints.