Add supplement list of compliant CNI plugins

Author: kgube

Standards/scs-XXXX-w1-kaas-networking.md

@@ -0,0 +1,27 @@
+---
+title: "KaaS Networking Standard: Implementation Notes"
+type: Supplement
+track: KaaS
+status: Draft
+supplements:
+  - scs-XXXX-v1-kaas-networking.md
+---
+## List of compliant CNI Plugins
+
+The Kubernetes Network Policy SIG maintains a [list of work-in-progress implementations](https://network-policy-api.sigs.k8s.io/implementations/) of the AdminNetworkPolicy and BaselineAdminNetworkPolicy resources.
+Besides their own validation implementation of [kube-network-policies](https://github.com/kubernetes-sigs/kube-network-policies), at the time of writing they list the following CNI plugins:
+
+- [OVN-Kubernetes](https://github.com/ovn-org/ovn-kubernetes/)
+- [Antrea](https://github.com/antrea-io/antrea/)
+- [KubeOVN](https://github.com/kubeovn/kube-ovn)
+- [Calico](https://github.com/projectcalico/calico)
+- [Cilium](https://github.com/cilium/cilium)
+
+All of these plugins also implement the basic NetworkPolicy API, and are therefore compliant both with the standard's requirements and recommendations.
+
+The CNI plugin [Flannel](https://github.com/flannel-io/flannel) does not support network policies by itself, but can be combined with Calico for policy enforcement.
+This configuration is known as [Canal](https://docs.tigera.io/calico/latest/getting-started/kubernetes/flannel/install-for-flannel) and will likely profit from Calico's support for AdminNetworkPolicy.
+
+There are more CNI plugins that support the NetworkPolicy API, but are not known to work on support of the AdminNetworkPolicy extensions.
+As such they are still compliant with the current version of the Standard.
+However, these seem to be either vendor-specific, like the [Azure CNI](https://learn.microsoft.com/de-de/azure/aks/configure-azure-cni), or unmaintained, like [Weave](https://github.com/weaveworks/weave).