Under the keyword 5G, the future network infrastructure targets to removal of limitations to current networks by addressing the challenges in managing, controlling and orchestrating a fully softwarized network and services running on the infrastructure. The use cases motivating 5G are so diverse and challenging that 5G networks must be customizable for a very broad range of individual scenarios. The Project SliceNet, part of the European 5G infrastructure PPP, is set to implement end-to-end multi-domain network slicing that provides a management plane for slices, as well as facilitating vertical business added value, coupled with optimized Quality of Experience (QoE) for the end users. This paper analyses the requirements derived from a set of use cases from different vertical industries including: Smart Grid Self-Healing, e-Health Smart/Connected Ambulance and Smart City, which collectively guide the development of the SliceNet architecture meeting the relevant Key Performance Indicators (KPIs) for these use cases.