OpenShift v4 Networking basics:

OpenShift v4, a Kubernetes-based container platform, introduces a robust and flexible networking model that supports the diverse needs of modern applications. Here are the basics of its networking:

Pod Networking: OpenShift uses a software-defined networking (SDN) approach to provide a unified cluster network where every Pod gets its own IP address. This enables communication between pods across different nodes without NAT.

Network Policies: Administrators and developers can use network policies to control the flow of traffic at the pod level within an OpenShift cluster.

Services: Services in OpenShift act as an abstraction layer, providing stable IP addresses and DNS names to manage access to the set of pods that make up an application.

Ingress and Routes: OpenShift has built-in support for managing external access to services in the cluster through routes and Ingress controllers, allowing users to reach services from outside the cluster.

Multitenancy: OpenShift provides network isolation by dividing the cluster into multiple virtual networks for different tenants or groups.

Service Mesh: OpenShift includes a service mesh layer for managing microservices-based applications, providing capabilities like traffic management, security, and observability.

Egress IP and Egress Network Policies: These features allow the control of outbound traffic from pods and the assignment of additional IP addresses to nodes for this traffic.

Network Plug-ins: OpenShift supports different CNI (Container Network Interface) plug-ins for various networking use cases, like OpenShift SDN, OVN-Kubernetes, etc.

Basic Commands to Verify Network in OpenShift
To verify and manage the network in OpenShift, you can use the OpenShift CLI (oc) commands. Here are some basic commands:

Check the Status of Nodes

oc get nodes

This command lists all the nodes in the cluster along with their status.

Examine Pod Networking

oc get pods -o wide

This displays all pods along with their IP addresses and the nodes they are running on.

View Network Policies

oc get networkpolicy

This command lists all network policies applied in the current project.

List Services

oc get svc

It shows all services in the current project, including ClusterIPs and Ports.

Inspect Routes

oc get routes

This command lists all the routes exposing services to external traffic.

Viewing Egress Network Policies

oc get egressnetworkpolicy
It lists egress network policies applied in the current project.

Describe Network Elements

For more detailed information about a specific resource (nodes, pods, services, routes), use the describe command. For example:

oc describe pod

Understanding these basics and commands can help you effectively manage and troubleshoot the network in an OpenShift v4 environment.