  We revisit multi-tenant network virtualization in data centers, and make the
case for tenant-specific virtual switches. In particular, tenant-specific
virtual switches allow cloud providers to extend fine-grained billing (known,
e.g., from serverless architectures) to the network, accounting not only for
IO, but also CPU or energy. We sketch an architecture and present economical
motivation and recent technological enablers. We also find that virtual
switches today do not offer sufficient multi-tenancy and can introduce
artificial performance bottlenecks, e.g., in load balancers. We conclude by
discussing additional use cases for tentant-specific switches.
