Multus is a Meta-Plugin CNI. Kubernetes only knows of and manages only one interface in every pod. For each pod (if CNI is being used), the CNI cmdAdd() is called once for each pod. When used, Multus is that one CNI. But Multus keeps a list of CNIs (or plugins), calls each CNI in its list, and returns the first CNI (default network) results back to Kubernetes. It thus enables injecting multiple interfaces/networks into a given pod.