Flannel - Container Networking Interface

Flannel is one of the most popular Container Network Interface (CNI) plugins used and deployed in the wild given it's really straightforward and simple to setup

A flat network gives every pod an address that other pods can route to directly, regardless of the node that runs it. Flannel commonly creates this connectivity with virtual networking and bridges, so pod-to-pod communication does not require each application to manage routes.

The extra encapsulation or routing work can add overhead on high-throughput paths; measure it before treating it as a bottleneck.

https://www.eficode.com/blog/debugging-kubernetes-networking

kubectl -n kube-system get configmap kube-flannel-cfg -o yaml