Flannel vs VMware NSX Container Plugin

Flannel is a free network fabric for containers designed for Kubernetes. A small flanneld agent on each host allocates a subnet lease from a configured address space, then forwards packets between hosts using a selected backend. Documented choices include VXLAN, host-gw, WireGuard and UDP, with VXLAN recommended. WireGuard encapsulates and encrypts packets using the in-kernel WireGuard implementation. Network configuration and subnet allocations can be stored in the Kubernetes API or directly in etcd. The project documents Kubernetes and Docker deployments, with Linux and Windows build instructions. Flannel does not enforce network policies itself, though its Helm chart can deploy a Kubernetes SIGs network policy controller alongside it. It runs as a privileged daemonset with access to the host network, so the security policy advises least privilege and keeping it updated. Security fixes are maintained for the latest release only, and the backend documentation says not to change a selected backend at runtime.

VMware NSX Container Plugin has no write-up on Specifiction yet; its figures are above.