  To implement the next Generation NodeBs (gNBs) that are present in every
Radio Access Network (RAN) slice subnet, Network Function Virtualization (NFV)
enables the deployment of some of the gNB components as Virtual Networks
Functions (VNFs). Deploying individual VNF instances for these components could
guarantee the customization of each RAN slice subnet. However, due to the
multiplicity of VNFs, the required amount of virtual resources will be greater
compared to the case where a single VNF instance carries the aggregated traffic
of all the RAN slice subnets. Sharing gNB components between RAN slice subnets
could optimize the trade-off between customization, isolation and resource
utilization. In this article, we shed light on the key aspects in the Third
Generation Partnership Project (3GPP)/NFV standards for sharing gNB components.
First, we identify four possible scenarios for sharing gNB components. Then, we
analyze the impact of sharing on the customization level of each RAN slice
subnet. Later, we determine the main factors that enable isolation between RAN
slice subnets. Finally, we propose a 3GPP/NFV-based description model to define
the lifecycle management of shared gNB components
