What is VXLAN? - Virtual Extensible LAN

VXLAN, Virtual Extensible LAN is an encapsulation protocol that runs an overlay network over an existing layer 3 infrastructure or underlay network.

VXLAN ( RFC7348 ) is used in the Cisco ACI fabric and allows network engineers to scale out cloud computing while isolating application. It is not limited to Cisco and was developed between Arista, VMware and Cisco. It can be run over any L3 transport and can even extend VLANs over long distances using a VXLAN gateway

This post will detail how VXLAN works and also answer some common question and general use cases

VXLAN Tutorial

VMware, Arista, and Cisco created the original VXLAN specification.
It is supported in Open vSwitch, and as of version 3.7, Linux also includes VXLAN support.

What problem is VXLAN addressing?

The current available VLAN space from the IEEE 802.1Q encapsulation perspective is limited to a 12-bit field, which provides 4096 VLANs. Within a standard switch you can only create 4096 VLANs providing logical separation of networks. When creating networks at scale this is a very limiting factor for multi tenant hosting environments.

By encapsulating the original Ethernet frame with a VXLAN header, the newly introduced addressing field offers 24-bits, thereby providing a much larger namespace with up to 16 Million Virtual Network Identifiers (VNIs) or segments.