Using high performance multicast

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

High performance multicast

The OpenShift SDN 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:

    1. apiVersion: sriovnetwork.openshift.io/v1
    2. kind: SriovNetworkNodePolicy
    3. metadata:
    4.   name: policy-example
    5.   namespace: openshift-sriov-network-operator
    6. spec:
    7.   resourceName: example
    8.   nodeSelector:
    9.     feature.node.kubernetes.io/network-sriov.capable: "true"
    10.   numVfs: 4
    11.   nicSelector:
    12.     vendor: "8086"
    13.     pfNames: ['ens803f0']
    14.     rootDevices: ['0000:86:00.0']

  2. Create a SriovNetwork object:

    1. apiVersion: sriovnetwork.openshift.io/v1
    2. kind: SriovNetwork
    3. metadata:
    4.   name: net-example
    5.   namespace: openshift-sriov-network-operator
    6. spec:
    7.   networkNamespace: default
    8.   ipam: | (1)
    9.     {
    10.       "type": "host-local", (1)
    11.       "subnet": "10.56.217.0/24",
    12.       "rangeStart": "10.56.217.171",
    13.       "rangeEnd": "10.56.217.181",
    14.       "routes": [
    15.         {"dst": "224.0.0.0/5"},
    16.         {"dst": "232.0.0.0/5"}
    17.       ],
    18.       "gateway": "10.56.217.1"
    19.     }
    20.   resourceName: example
    1If 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:

    1. apiVersion: v1
    2. kind: Pod
    3. metadata:
    4.   name: testpmd
    5.   namespace: default
    6.   annotations:
    7.     k8s.v1.cni.cncf.io/networks: nic1
    8. spec:
    9.   containers:
    10.   - name: example
    11.     image: rhel7:latest
    12.     securityContext:
    13.       capabilities:
    14.         add: ["NET_ADMIN"] (1)
    15.     command: [ "sleep", "infinity"]
    1The 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.