VXLAN (Virtual Extensible LAN)

VXLAN, or Virtual Extensible LAN, is a technology used to extend Layer 2 (Ethernet) networks over Layer 3 (IP networks). It was developed to address the limitations of traditional VLANs, which are constrained by the 12-bit VLAN ID field in the Ethernet header, allowing for only 4096 unique VLANs.

Here are some key aspects of VXLAN:

1. Encapsulation: VXLAN encapsulates Layer 2 Ethernet frames within UDP packets. This allows it to traverse Layer 3 networks, which is beneficial for network virtualization and multi-tenant environments.

2. VXLAN ID (VNI): VXLAN introduces a 24-bit VXLAN Network Identifier (VNI) to overcome the limitation of VLAN IDs. This allows for up to 16 million unique VXLAN segments, significantly increasing scalability compared to VLANs.

3. Underlay Network: VXLAN operates over an IP underlay network (usually IPv4 or IPv6), which means it can leverage existing network infrastructure without requiring significant changes to the underlying physical network.

4. Overlay Network: VXLAN creates an overlay network where virtual Layer 2 segments (VXLAN segments) can span across physical network boundaries. This is particularly useful in data centers and cloud environments where virtual machine mobility and workload flexibility are essential.

5. Control Plane: VXLAN does not define a specific control plane protocol. It typically relies on existing routing protocols (like BGP or OSPF) or a controller-based approach for mapping VXLAN segments to VLANs or other network policies.

6. Use Cases: VXLAN is widely used in cloud computing environments, especially in virtualized data centers (e.g., VMware NSX) and for connecting geographically dispersed data centers over a wide-area network (WAN).

Overall, VXLAN provides a scalable and flexible solution for network virtualization, allowing organizations to overcome the limitations of traditional VLANs and improve the efficiency and agility of their network infrastructures.