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Part of Red Hat OpenShift Networking, OpenShift SDN is a network plugin that uses a software-defined networking (SDN) approach to provide a unified cluster network that enables communication between pods across the OKD cluster. This pod network is established and maintained by OpenShift SDN, which configures an overlay network using Open vSwitch (OVS).

OpenShift SDN network isolation modes

OpenShift SDN provides three SDN modes for configuring the pod network:

  • Network policy mode allows project administrators to configure their own isolation policies using NetworkPolicy objects. Network policy is the default mode in OKD 4.12.

  • Multitenant mode provides project-level isolation for pods and services. Pods from different projects cannot send packets to or receive packets from pods and services of a different project. You can disable isolation for a project, allowing it to send network traffic to all pods and services in the entire cluster and receive network traffic from those pods and services.

  • Subnet mode provides a flat pod network where every pod can communicate with every other pod and service. The network policy mode provides the same functionality as subnet mode.

Supported network plugin feature matrix

Red Hat OpenShift Networking offers two options for the network plugin, OpenShift SDN and OVN-Kubernetes, for the network plugin. The following table summarizes the current feature support for both network plugins:

Table 1. Default CNI network plugin feature comparison
Feature OpenShift SDN OVN-Kubernetes

Egress IPs

Supported

Supported

Egress firewall [1]

Supported

Supported

Egress router

Supported

Supported [2]

Hybrid networking

Not supported

Supported

IPsec encryption

Not supported

Supported

IPv6

Not supported

Supported [3]

Kubernetes network policy

Partially supported [4]

Supported

Kubernetes network policy logs

Not supported

Supported

Multicast

Supported

Supported

Hardware offloading

Not supported

Supported

  1. Egress firewall is also known as egress network policy in OpenShift SDN. This is not the same as network policy egress.

  2. Egress router for OVN-Kubernetes supports only redirect mode.

  3. IPv6 is supported only on bare metal, IBM Power, and IBM Z clusters.

  4. Network policy for OpenShift SDN does not support egress rules and some ipBlock rules.