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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.

Related Terms

ARP (Address Resolution Protocol)
A protocol that maps IP addresses to physical MAC addresses on a local network segment.
SNMP (Simple Network Management Protocol)
A protocol for monitoring and managing network devices like routers, switches, servers, and printers remotely.
MTU (Maximum Transmission Unit)
The maximum size of a data packet that can be transmitted over a network without fragmentation.
Proxy Server
An intermediary server that forwards requests between clients and destination servers, providing caching, filtering, or anonymity.
Port
A numbered endpoint (0-65535) that identifies specific processes or services on a networked computer for communication.
DNS over HTTPS (DoH)
A protocol that encrypts DNS queries by sending them over HTTPS, preventing eavesdropping and manipulation of DNS traffic.
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