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About the OpenShift SDN network plugin

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 OpenShift Container Platform cluster. This pod network is established and maintained by OpenShift SDN, which configures an overlay network using Open vSwitch (OVS).

OpenShift SDN CNI is deprecated as of OpenShift Container Platform 4.14. As of OpenShift Container Platform 4.15, the network plugin is not an option for new installations. In a subsequent future release, the OpenShift SDN network plugin is planned to be removed and no longer supported. Red Hat will provide bug fixes and support for this feature until it is removed, but this feature will no longer receive enhancements. As an alternative to OpenShift SDN CNI, you can use OVN Kubernetes CNI instead. For more information, see OpenShift SDN CNI removal.

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 OpenShift Container Platform 4.16.

  • 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

Supported

Supported [1]

Egress router

Supported

Supported [2]

Hybrid networking

Not supported

Supported

IPsec encryption for intra-cluster communication

Not supported

Supported

IPv4 single-stack

Supported

Supported

IPv6 single-stack

Not supported

Supported [3]

IPv4/IPv6 dual-stack

Not Supported

Supported [4]

IPv6/IPv4 dual-stack

Not supported

Supported [5]

Kubernetes network policy

Supported

Supported

Kubernetes network policy logs

Not supported

Supported

Hardware offloading

Not supported

Supported

Multicast

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 single-stack networking on a bare-metal platform.

  4. IPv4/IPv6 dual-stack networking on bare-metal, VMware vSphere (installer-provisioned infrastructure installations only), IBM Power®, IBM Z®, and RHOSP platforms.

  5. IPv6/IPv4 dual-stack networking on bare-metal, VMware vSphere (installer-provisioned infrastructure installations only), and IBM Power® platforms.