concept pod network in category openshift
This is an excerpt from Manning's book OpenShift in Action.
When you initially deployed OpenShift, a private network called the pod network was created. Each pod in your OpenShift cluster is assigned an IP address on the pod network when it’s deployed. This IP address is used to communicate with each pod across the cluster. The pod network spans all nodes in your cluster and was extended to your second application node when that was added to the cluster (see figure 10.1).
The pod network uses the 10.128.0.0/14 classless inter-domain routing (CIDR, (defined at http://mng.bz/28or) IP address block by default. Each node in the cluster is assigned a /23 CIDR IP address range from the pod network block. That means, by default, that each application node in OpenShift can accommodate a maximum of 512 pods. The IP ranges for each node are controlled by OpenFlow, a component in OpenShift’s networking solution. OpenFlow (https://www.sdxcentral.com/sdn/definitions/what-is-openflow/) is a software-defined networking control-plane manager that OpenShift uses to route network traffic in the cluster without having to change the configuration of the host’s networking stack. Open control lets OpenShift maintain the IP address ranges for each host without having to alter the application node’s network routing tables. To see information about the pod network, including the IP ranges allocated to each node, run the oc get hostsubnet command:
