1. A non-provider backbone bridging multi-tenant datacenter having Layer 2 architecture to maintain original client Layer 2 configurations and permit software defined networking, comprising: a plurality of physical client systems in a first datacenter each physical client system having a set of physical infrastructure resources and an original Layer 2 configuration; and a first cloud computing environment established in the first datacenter having Layer 2 architecture to maintain the original client Layer 2 configurations, and coupled to the plurality of physical client systems by Open System Interconnection (OSI) Layer 2, prior to an OSI Layer 3 connection, as the physical connection of a data channel for the transfer of data frames, each frame having a plurality of OSI Layer 2 tags applied prior to a Layer 3 activity permitting at least two client systems to have overlapping Virtual Local Area Networks (VLANs) and or overlapping Internet Protocol (IP) address ranges at Layer 3 as frame transmission is distinct from packet transmission, the first cloud computing environment thereby virtually extending the set of physical infrastructure resources of each physical client system and each client system maintains client's original Layer 2 configuration, and may self direct software defined networking, wherein the OSI Layer 2 tags are selected from a group consisting of Segment Identification (ID) Tags and Global VLAN Tags.