Protocol Lab #18: Hands-On VXLAN Tutorial Shows How Overlay Traffic Is Visible on the Wire

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A new hands-on networking lab from the Protocol Lab series walks learners through building a point-to-point VXLAN overlay between two container nodes using VNI 100 over UDP port 4789. Unlike the WireGuard lab covered in Lab 16, VXLAN encapsulates Ethernet frames as a Layer-2 overlay without encrypting them, meaning the inner packet remains readable on the underlay. Participants capture live traffic to observe both the VXLAN header and the inner ICMP echo in plaintext, reinforcing the distinction between encapsulation and encryption. The lab also clarifies the difference between overlay addressing (10.200.0.x) and underlay addressing (10.0.0.x), and references RFC 7348 for the VXLAN frame format and VTEP roles. All lab materials, including topologies, configs, and scripts, are freely available on GitHub, and the exercise is estimated to take 45–60 minutes on a Linux environment.

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