In the information technology field often when a new technology is created to address a need, an enhancement or complementary technology is created.
The best example of this is virtualization (network and resources) in the data center. Prior to virtualization, traditional network segmentation was provided through VLANs (Virtual Local Area Networks) where a set of hosts or a single host would be assigned to a different VLAN ID in order to segment them from each other. If these hosts wanted to communicate with each other; inter-vlan routing would be required
There are inherent shortcomings when using VLANs, such as inefficient network inter-links, spanning tree limitations, physical location of devices, limited number of VLANs (4,094), multi-tenant environments, and ToR (Top of Rack) switch scalability. VLANs have become a limiting factor for IT departments and providers as they look to build efficient and highly scalable multitenant data centers where server virtualization is a key critical component.