Selecting the Host NIC, MTU, and Traffic Mirrors

If the host machine has multiple NICs, Kube-OVN selects the NIC of the default route as the NIC for cross-node communication between containers by default and establishes the corresponding Geneve tunnel.

Extra payloads are occupied when the Geneve tunnel is used for overlay network encapsulation. When creating a container NIC, Kube-OVN adjusts the maximum transmission unit (MTU) of the container NIC based on the MTU of the selected NIC. The default MTU is the MTU of the host NIC minus 100.

By default, Kube-OVN creates a mirror0 NIC on each node to copy the network traffic of all containers on the current node. You can use tcpdump and other tools to analyze the traffic.

If you need to customize the preceding functions, you can configure cni-server in the kube-ovn.yaml file.