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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

SDN (Software-Defined Networking)
An approach that separates the network control plane from the data plane, enabling centralized, programmable network management.
Network Bridge
A device or software that connects two or more network segments at the data link layer, forwarding traffic based on MAC addresses.
VLAN (Virtual LAN)
A logical grouping of network devices that creates separate broadcast domains on the same physical network infrastructure.
NAT (Network Address Translation)
A method of mapping private IP addresses to public IP addresses, allowing multiple devices to share a single public IP.
Token Bucket Algorithm
A rate limiting algorithm that allows burst traffic by accumulating tokens at a fixed rate and consuming them per request.
Network Packet
A formatted unit of data carried over a network, containing headers with routing information and a payload with the actual data.
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