Kubernetes with Cilium BGP: services reachable without Ingress

One of the advantages of using Cilium as the CNI in Kubernetes is its native BGP support. It lets you advertise ClusterIPs and LoadBalancer IPs directly to the LAN router, making services reachable without needing Ingress or NodePort.

The problem

In a standard Kubernetes cluster, pods and services live on internal networks that are not reachable from outside the cluster. Getting to them requires NodePort, Ingress or an external LoadBalancer.

With Cilium BGP, the pod CIDRs and service CIDRs are advertised over BGP to the upstream router, making the whole cluster network routable from the LAN.

Work in progress — full configurations for RKE2 + CRS327 coming soon.