text: When a node is added to the cluster, the OpenShift SDN registers the local host with the 
  registry on master to allocate an open subnet to the node. 
  
  Then, OpenShift SDN creates and configures the following network devices: 
  
  (cid:2) br0: Open Virtual Switch (OVS) bridge device to which pod containers are attached. 
  OpenShift SDN also configures a set of non-subnet-specific flow rules on this bridge. 
  
  (cid:2) tun0: OVS internal port (port 2 on br0). This port is assigned the cluster subnet gateway 
  address and is used for external network access. OpenShift SDN configures netfilter and 
  routing rules to enable access from the cluster subnet to the external network by way of 
  NAT. 
  
  (cid:2) vxlan_sys_4789: OVS VXLAN device (port 1 on br0), which provides access to containers 
  
  on remote nodes. It is referred to as*vxlan0*in the OVS rules. 
  
  When a pod is started on the host, OpenShift SDN completes the following process: 
  
  1. Assigns the pod an open IP address from the node’s cluster subnet. 
  
  2. Attaches the host side of the pod’s veth interface pair to the OVS bridge br0. 
  
  3. Adds OpenFlow rules to the OVS database to route traffic that is addressed to the new 
  
  pod to the correct OVS port. In the case, of the ovs-multitenant plug-in, it adds OpenFlow 
  rules to tag traffic that is coming from the Pod with the Pod’s VNID, and to allow traffic into 
  the Pod if the traffic’s VNID matches the Pod’s VNID (or is the privileged VNID 0). 
  Non-matching traffic is filtered out by a generic rule. 