11.7. Using high performance multicast

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

11.7.1. Configuring high performance multicast

The OpenShift SDN default Container Network Interface (CNI) network provider 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 OpenShift Container Platform.

11.7.2. Using 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", 2
      "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 2
    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.