[1] It is based on the kernel technology eBPF, originally for better networking performance, and now leverages many additional features for different use cases.

[9] As the cloud native ecosystem expanded, Cilium added new projects and features to address new problems in the space.

The table below summarises some of the most significant milestones of this evolution: Cilium was accepted into the Cloud Native Computing Foundation on October 13th, 2021 as an incubation-level project.

Cilium implements distributed load balancing for traffic between Pods and to external services, and is able to fully replace kube-proxy,[53] using XDP, socket-based load-balancing and efficient hash tables in eBPF.

It also supports advanced functionality like integrated ingress and egress gateways,[54] bandwidth management, a stand-alone load balancer, and service mesh.

[63] Tetragon is a flexible Kubernetes-aware security observability and runtime enforcement tool that applies policy and filtering directly with eBPF.

Under the hood, pwru attaches eBPF debugging programs to all Linux kernel functions which are responsible for processing network packets.

Cilium began as a networking project and has many features that allow it to provide a consistent connectivity experience from Kubernetes workloads to virtual machines and physical servers running in the cloud, on-premises, or at the edge.