VXLAN (Virtual Extensible LAN)

VXLAN, short for Virtual Extensible LAN, is a modern network technology designed to solve scalability problems in large cloud computing environments. At its core, VXLAN is about creating a network within a network (often called an overlay network) that allows for the creation of thousands, even millions, of separate virtual networks.

Traditionally, networks have been limited by VLAN technology, which can only support up to 4,094 unique network identifiers due to its 12-bit VLAN ID limitation. VXLAN pushes past these boundaries by using a 24-bit identifier known as a VNID (VXLAN Network Identifier), allowing for approximately 16 million unique identifiers. This massive leap in scalability makes VXLAN an excellent choice for sprawling cloud infrastructures where isolation between numerous tenant networks is a must.

VXLAN operates by encapsulating traditional Layer 2 Ethernet frames into Layer 4 UDP packets. This encapsulation allows VXLAN to tunnel these frames over an existing IP network, seamlessly connecting data center networks that might be physically located far apart. Each encapsulated packet travels across the network to VXLAN Tunnel Endpoints (VTEPs), which sit at the edge of VXLAN networks, encapsulating and de-encapsulating packets as they enter or exit the network.

The technology was developed through a collaboration of industry heavyweights including VMware, Cisco, and Arista Networks, with significant contributions from other players in the networking space. Today, VXLAN is documented and standardized by the Internet Engineering Task Force (IETF) in RFC 7348.

One of the key features of VXLAN is its use of both multicast and unicast for managing broadcast, unknown-unicast, and multicast traffic. This versatility allows VXLAN to be highly efficient in a variety of network configurations and scales.