What is VXLAN and its role in data center networking?
Why Interviewers Ask This
Advanced questions like this reveal whether a candidate has internalized Networking deeply enough to make architectural decisions. Strong answers demonstrate both breadth and depth of experience.
Answer
VXLAN (Virtual Extensible LAN) is a network virtualization technology that encapsulates Layer 2 Ethernet frames inside Layer 4 UDP packets, allowing Layer 2 networks to span across Layer 3 (routed) infrastructure. VXLAN solves a critical data center problem: VLANs are limited to 4094 IDs and cannot natively cross Layer 3 boundaries. VXLAN provides 16 million segment IDs (VNI — VXLAN Network Identifiers) and extends Layer 2 across the entire data center or cloud. VTEP (VXLAN Tunnel Endpoint) devices encapsulate/decapsulate VXLAN traffic. VTEPs can be software (in hypervisors — VMware vSphere, Linux kernel VXLAN) or hardware (on switches). VXLAN uses UDP port 4789. In modern cloud environments (AWS, Azure, Google Cloud), VXLAN and similar overlay technologies create virtual networks for tenants. EVPN (Ethernet VPN) is often combined with VXLAN as the control plane for MAC/IP learning.
Common Mistake
Candidates often give textbook answers here. Interviewers are more impressed when you relate the concept to a specific problem you solved in a real Networking project.
Previous
What is SDN (Software-Defined Networking)?
Next
What is BGP communities and route filtering?