Using high performance multicast

You can use multicast on your Single Root I/O Virtualization (SR-IOV) hardware network.

Before you perform any tasks in the following documentation, ensure that you installed the SR-IOV Network Operator.

High performance multicast

The OVN-Kubernetes network plugin supports multicast between pods on the default network. This is best used for low-bandwidth coordination or service discovery, and not high-bandwidth applications.

For applications such as streaming media, such as Internet Protocol television (IPTV) and multipoint videoconferencing, you can use Single Root I/O Virtualization (SR-IOV) hardware to provide near-native performance.

When using additional SR-IOV interfaces for multicast:

• Multicast packages must be sent or received by a pod through the additional SR-IOV interface.
• The physical network which connects the SR-IOV interfaces decides the multicast routing and topology, which is not controlled by OpenShift Container Platform.

Configure an SR-IOV interface for multicast

The following procedure creates an example SR-IOV interface for multicast.

Prerequisites

• Install the OpenShift CLI (oc).
• You must log in to the cluster with a user that has the cluster-admin role.

Procedure

1. Create a SriovNetworkNodePolicy object:

   apiVersion: sriovnetwork.openshift.io/v1
   kind: SriovNetworkNodePolicy
   metadata:
     name: policy-example
     namespace: openshift-sriov-network-operator
   spec:
     resourceName: example
     nodeSelector:
       feature.node.kubernetes.io/network-sriov.capable: "true"
     numVfs: 4
     nicSelector:
       vendor: "8086"
       pfNames: ['ens803f0']
       rootDevices: ['0000:86:00.0']

2. Create a SriovNetwork object:

   apiVersion: sriovnetwork.openshift.io/v1
   kind: SriovNetwork
   metadata:
     name: net-example
     namespace: openshift-sriov-network-operator
   spec:
     networkNamespace: default
     ipam: |
       {
         "type": "host-local",
         "subnet": "10.56.217.0/24",
         "rangeStart": "10.56.217.171",
         "rangeEnd": "10.56.217.181",
         "routes": [
           {"dst": "224.0.0.0/5"},
           {"dst": "232.0.0.0/5"}
         ],
         "gateway": "10.56.217.1"
       }
     resourceName: example

   • If you choose to configure DHCP as IPAM, ensure that you provision the following default routes through your DHCP server: 224.0.0.0/5 and 232.0.0.0/5. This is to override the static multicast route set by the default network provider.

3. Create a pod with multicast application:

   apiVersion: v1
   kind: Pod
   metadata:
     name: testpmd
     namespace: default
     annotations:
       k8s.v1.cni.cncf.io/networks: nic1
   spec:
     containers:
     - name: example
       image: rhel7:latest
       securityContext:
         capabilities:
           add: ["NET_ADMIN"]
       command: [ "sleep", "infinity"]

   • The NET_ADMIN capability is required only if your application needs to assign the multicast IP address to the SR-IOV interface. Otherwise, you can omit it.