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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, like Internet Protocol television (IPTV) and multipoint videoconferencing, you can utilize 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 OKD.

Configuring an SR-IOV interface for multicast

The follow 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: | (1)
    {
      "type": "host-local", (1)
      "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
    1 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"] (1)
    command: [ "sleep", "infinity"]
    1 The NET_ADMIN capability is required only if your application needs to assign the multicast IP address to the SR-IOV interface. Otherwise, it can be omitted.