NSX leverages the overlay model, where layer 2 connectivity between virtual machines (VMs) is achieved using point-to-point tunnels over a traditional routed IP network. This provides the last building block for a complete virtualization of the datacenter, where a solution can be deployed programmatically with no dependency on the physical infrastructure.
Even in highly virtualized environments, customers often have some few workloads that cannot be virtualized, because of licensing or application-specific reasons. Those VLAN backed workloads typically communicate with overlay backed VMs at layer 3, through Tier0 gateways instantiated on the NSX edges. However, there are some scenarios where layer 2 connectivity is required between VMs and physical devices, and this paper introduces the NSX edge bridge, a service that can be instantiated on an edge for that purpose.