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Networking Advanced

What is Overlay Network?

A virtual network built on top of an existing physical network, enabling features like container networking and VPNs.

Overlay networks create logical network topologies independent of the underlying physical infrastructure. They encapsulate packets from the overlay network inside packets of the underlay network (tunneling). Technologies include VXLAN (extending Layer 2 across Layer 3 boundaries), WireGuard/IPsec (VPN tunnels), and container networking (Flannel, Calico, Weave). In Kubernetes, overlay networks enable pods on different physical hosts to communicate as if on the same LAN. Benefits include network isolation, simplified addressing, and infrastructure independence. The trade-off is encapsulation overhead reducing effective MTU and adding latency.

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