In the early days of network virtualization, the emerging platforms were described in rather simple terms, largely taken from the data center market, where the approach had originated. Replacing integrated, single-purpose appliances with software running on COTS hardware was the main theme, with the visionaries envisaging a shift to the cloud. But these early discussions tended to downplay what is unique about virtualizing a network. The network hardware and software itself would be particularly challenging to replace without compromising performance, and some of it, especially related to the RAN, would have to remain. Only a multi-faceted approach to virtualizing the access network – wireless or wireline – will deliver the promised results, but that will also mean investing in multiple…