Container Network Interface (CNI)

• Specification to configure network interfaces in Liunx Containers
• Concerned with connecting (add) and disconnecting(delete) containers to the network
• It is network model with connectivity rules:
  POD <======> POD means pod to pod communication
  NODE <=======> POD means Node to pod communication
• CNI comes with networking plugins like BRIDGE, VLAN, IPVLAN,MACVLAN, DHCP, host-local
• Third-Party plugins like Calico, Weave network, flannel, NSX

 Why CNI

• Networking can be highly environment-specific
• Different projects seek to solve the networking challenges – with potential overlap
• Makes standards for common networking

CNI in Kubernetes

• /opt/cni/bin/ show all the supported cni pluggins executeables
• ls /etc/cni/net.d/ shows which plugin is used
• cat /etc/cni/net.d/10-calico.conflist (if you are using calico plugin) gives more information about the plugin