openshift-docs/modules/nw-enabling-multicast.adoc

// Module included in the following assemblies:
//
// * networking/ovn_kubernetes_network_provider/enabling-multicast.adoc

ifeval::["{context}" == "openshift-sdn-enabling-multicast"]
:namespace: netnamespace
:annotation: netnamespace.network.openshift.io/multicast-enabled=true
endif::[]
ifeval::["{context}" == "ovn-kubernetes-enabling-multicast"]
:namespace: namespace
:annotation: k8s.ovn.org/multicast-enabled=true
endif::[]

:_mod-docs-content-type: PROCEDURE
[id="nw-enabling-multicast_{context}"]
= Enabling multicast between pods

[role="_abstract"]
You can enable multicast between pods for your project.

.Prerequisites

* Install the {oc-first}.
* You must log in to the cluster with a user that has the `cluster-admin`
ifdef::openshift-rosa,openshift-dedicated[]
or the `dedicated-admin`
endif::[]
role.

.Procedure

* Run the following command to enable multicast for a project. Replace `<namespace>` with the namespace for the project you want to enable multicast for.
+
[source,terminal,subs="attributes+"]
----
$ oc annotate {namespace} <namespace> \
    {annotation}
----
ifeval::["{context}" == "ovn-kubernetes-enabling-multicast"]
+
[TIP]
====
You can alternatively apply the following YAML to add the annotation:

[source,yaml]
----
apiVersion: v1
kind: Namespace
metadata:
  name: <namespace>
  annotations:
    k8s.ovn.org/multicast-enabled: "true"
----
====
endif::[]

.Verification

To verify that multicast is enabled for a project, complete the following procedure:

. Change your current project to the project that you enabled multicast for. Replace `<project>` with the project name.
+
[source,terminal]
----
$ oc project <project>
----

. Create a pod to act as a multicast receiver:
+
[source,terminal]
----
$ cat <<EOF| oc create -f -
apiVersion: v1
kind: Pod
metadata:
  name: mlistener
  labels:
    app: multicast-verify
spec:
  containers:
    - name: mlistener
      image: registry.access.redhat.com/ubi9
      command: ["/bin/sh", "-c"]
      args:
        ["dnf -y install socat hostname && sleep inf"]
      ports:
        - containerPort: 30102
          name: mlistener
          protocol: UDP
EOF
----

. Create a pod to act as a multicast sender:
+
[source,terminal]
----
$ cat <<EOF| oc create -f -
apiVersion: v1
kind: Pod
metadata:
  name: msender
  labels:
    app: multicast-verify
spec:
  containers:
    - name: msender
      image: registry.access.redhat.com/ubi9
      command: ["/bin/sh", "-c"]
      args:
        ["dnf -y install socat && sleep inf"]
EOF
----

. In a new terminal window or tab, start the multicast listener.

.. Get the IP address for the Pod:
+
[source,terminal]
----
$ POD_IP=$(oc get pods mlistener -o jsonpath='{.status.podIP}')
----

.. Start the multicast listener by entering the following command:
+
[source,terminal]
----
$ oc exec mlistener -i -t -- \
    socat UDP4-RECVFROM:30102,ip-add-membership=224.1.0.1:$POD_IP,fork EXEC:hostname
----

. Start the multicast transmitter.

.. Get the pod network IP address range:
+
[source,terminal]
----
$ CIDR=$(oc get Network.config.openshift.io cluster \
    -o jsonpath='{.status.clusterNetwork[0].cidr}')
----

.. To send a multicast message, enter the following command:
+
[source,terminal]
----
$ oc exec msender -i -t -- \
    /bin/bash -c "echo | socat STDIO UDP4-DATAGRAM:224.1.0.1:30102,range=$CIDR,ip-multicast-ttl=64"
----
+
If multicast is working, the previous command returns the following output:
+
[source,text]
----
mlistener
----

ifeval::["{context}" == "openshift-sdn-enabling-multicast"]
:!annotation:
:!namespace:
endif::[]
ifeval::["{context}" == "ovn-kubernetes-enabling-multicast"]
:!annotation:
:!namespace:
endif::[]