NSX-T Terminologies: OVS, pNIC, vNIC, VNI & TEP

Today we are going to discuss about the NSX-T terminologies which are used when we study NSX-T or deploying NSX-T. As you may know that Software that runs on the hypervisor and provides physical traffic forwarding.

The hostswitch or OVS is invisible to the tenant network administrator and provides the  underlying forwarding service that each logical switch relies on.

To achieve network  virtualization, a network controller must configure the hypervisor hostswitches with network flow tables that form the logical broadcast domains the tenant administrators defined when they created and configured their logical switches.

Each logical broadcast domain is implemented by tunneling VM-to-VM and VM-to-logical  router traffic, using the tunnel encapsulation protocol Geneve. 

Fig 1.1- VMware NSX-T 2.7

Open vSwitch (OVS)
Open source software switch that acts as a hypervisor hostswitch within XenServer, Xen,  KVM and other Linux-based hypervisors. NSX Edge switching components are based on  OVS.

Overlay Logical Network
Logical network implemented using Layer 2-in-Layer 3 tunneling such that the topology  seen by VMs is decoupled from that of the physical network.

Physical Interface (pNIC)
Network interface on a physical server that a hypervisor is installed on.

VM Interface (vNIC)
Network interface on a virtual machine that provides connectivity between the virtual  guest operating system and the standard vSwitch or vSphere Distributed Switch. The  vNIC can be attached to a logical port. You can identify a vNIC based on its Unique ID  (UUID). The vNIC is equivalent to a network interface card (NIC) on a physical machine.

Virtual Network Interface (VNI)
The network identifier associated with a given logical switch. As Layer 2 segments are  created in NSX, an associated VNI is allocated. This VNI is used in the encapsulated  overlay packet, and facilitates Layer 2 separation.

Tunnel End Point (TEP)
Tunnel endpoints enable hypervisor hosts to participate in an NSX-T network overlay. The NSX-T overlay deploys a Layer 2 network over an existing  physical network fabric by encapsulating frames inside of packets, and transferring the  encapsulated packets over the underlying transport network. 

The underlying transport  network can consist of either Layer 2 or Layer 3 networks. The TEP is the connection  point at which encapsulation and decapsulation takes place.