What is VXLAN? Simplified.

👉 It is Virtual Extensible LAN.

👉 VXLAN is a network virtualization technology that provides mechanisms to aggregate and tunnel multiple layer 2 segments across a layer 3 network.

VXLAN Introduction

👉 As an SDN technology, it is heavily used in ACI infrastructure to extend Layer 2 domains (VLANs) over a Layer 3 network (IP Subnet).

👉 Runs on default UDP port number 4789.

👉 Tunnels L2 frames in L3 packets between two Virtual Tunnel End Points (VTEP).

👉 VTEP is like a gateway that does L2 to L3 and L3 to L2 translations by encapsulating an L2 frame into an L3 packet at source and decapsulating an L3 packet into an L2 frame at destination.

👉 Uses existing Layer 2 mechanisms like flooding, and dynamic MAC address learning to discover remote VTEPs and learn remote host MAC addresses and MAC-to-VTEP mappings for each VXLAN segment.

👉 VXLAN includes a 24-bit VNI in its VXLAN header, that can support up to 16 million L2 segments. It means there can be up to 16 million VXLANs as opposed to only 4094 VLANs.

👉 VNI is VXLAN Network Identifier that uniquely identifies an L2 segment mapped to a VLAN.

👉 VXLAN is vendor neutral, and most vendors like Cisco, VMware Juniper, Huawei, Citrix, Red Hat and Arista support its implementation. As per IETF RFC 7348, it is defined as a framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks.

I hope that was informative! I will cover VXLAN implementation in another post soon.

Thank you!