Customers with a wired network based on SD-Access fabric have two options for integrating wireless access:
+ SD-Access Wireless Architecture
+ Cisco Unified Wireless Network Wireless Over the Top (OTT)
OTT basically involves running traditional wireless on top of a fabric wired network.
Why would you deploy Cisco Unified Wireless Network wireless OTT? There are two primary reasons:
...
2. Another reason for deploying wireless OTT could be that customer doesn't want or cannot migrate to fabric for wireless.
Reference: https://www.cisco.com/c/dam/en/us/td/docs/cloud-systems-management/network- automation-and-management/dna-center/deploy-guide/cisco-dna-center-sd-access-wl-dg.pdf

A virtual machine (VM) is a software emulation of a physical server with an operating system.
From an application's point of view, the VM provides the look
and feel of a real physical server, including all its components, such as CPU, memory, and network interface cards (NICs).
The virtualization software that creates VMs and performs the hardware abstraction that allows multiple VMs to run concurrently is known as a hypervisor.
There are two types of hypervisors: type 1 and type 2 hypervisor.
In type 1 hypervisor (or native hypervisor), the hypervisor is installed directly on the physical server. Then instances of an operating system (OS) are installed on the hypervisor. Type 1 hypervisor has direct access to the hardware resources. Therefore they are more efficient than hosted architectures. Some examples of type 1 hypervisor are VMware vSphere/ESXi, Oracle VM Server, KVM and Microsoft Hyper-V.
In contrast to type 1 hypervisor, a type 2 hypervisor (or hosted hypervisor) runs on top of an operating system and not the physical hardware directly. answer 'Each virtual machine requires a unique IP and MAC addresses to be able to reach to other nodes' big advantage of Type 2 hypervisors is that management console software is not required. Examples of type 2 hypervisor are VMware Workstation (which can run on Windows, Mac and Linux) or Microsoft Virtual PC (only runs on Windows).

Fabric Enabled WLC:
Fabric enabled WLC is integrated with LISP control plane. This WLC is responsible for AP image /Config, Radio Resource Management, Client Session management and roaming and all other wireless control plane functions.
For WLC Fabric Integration:
Wireless Client MAC address is used as EID
It inform about Wireless MAC address with its other information like SGT and Virtual Network Information
VN information is mapped to VLAN on FEs
WLC is responsible for updating Host Database tracking DB with roaming information