Documentation/network/multicast.rst
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.. _enable_multicast:
Multicast Support in Cilium (Beta)
.. include:: ../beta.rst
The multicast capability allows user application to distribute data feeds to multiple consumers in the Kubernetes cluster. The container network multicast transmission technology based on eBPF focuses on solving the problem of efficient multicast transmission in the container network and provides support for multiple multicast protocols.
This document explains how to enable multicast support and configure Cilium and CiliumNode with multicast group IP addresses and subscribers.
This guide assumes that Cilium has been correctly installed in your
Kubernetes cluster. Please see :ref:k8s_quick_install for more
information. If unsure, run cilium status and validate that Cilium is up
and running. This guide also assumes Cilium is configured with vxlan mode,
which is required when using multicast capability.
Multicast only works on kernels >= 5.10 for AMD64, and on kernels >= 6.0 for AArch64.
Multicast support can be enabled by updating cilium-config ConfigMap as following:
.. code-block:: shell-session
$ cilium config set multicast-enabled true ✨ Patching ConfigMap cilium-config with multicast-enabled=true... ♻️ Restarted Cilium pods
To use multicast with Cilium, we need to configure multicast group IP addresses and
subscriber list based on the application requirements. This is done by running
cilium-dbg command in each cilium-agent pod.
Then, multicast subscriber pods can send out IGMP join and multicast
sender pods can start sending multicast stream.
As an example, the following guide uses 239.255.0.1 multicast group address.
Get all CiliumNode IP addresses to be set as multicast subscribers:
.. code-block:: shell-session
$ kubectl get ciliumnodes.cilium.io NAME CILIUMINTERNALIP INTERNALIP AGE kind-control-plane 10.244.0.72 172.19.0.2 16m kind-worker 10.244.1.86 172.19.0.3 16m
To set multicast IP address, enable multicast BPF maps in each cilium-agent:
.. code-block:: shell-session
$ cilium-dbg bpf multicast group add 239.255.0.1
$ cilium-dbg bpf multicast group list Group Address 239.255.0.1
Then, set the subscriber IP addresses in each cilium-agent:
.. code-block:: shell-session
$ cilium-dbg bpf multicast subscriber add 239.255.0.1 10.244.1.86 $ cilium-dbg bpf multicast subscriber list all Group Subscriber Type 239.255.0.1 10.244.1.86 Remote Node
$ cilium-dbg bpf multicast subscriber add 239.255.0.1 10.244.0.72
.. note::
This multicast subscriber IP addresses are different CiliumNode IP addresses than your own one.
To make all nodes join a specified multicast group, use the cilium multicast command.
You can also get information about multicast groups and subscribers cluster-wide.
.. code-block:: shell-session
$ cilium multicast add --group-ip 239.255.0.1
$ cilium multicast list subscriber --all Node Group Subscriber Type cl-worker 239.255.0.1 10.244.0.196 Remote Node cl-control-plane 239.255.0.1 10.244.1.122 Remote Node
When you want to remove multicast IP addresses and subscriber list, run the following commands in the cilium-agent.
.. code-block:: shell-session
$ cilium-dbg bpf multicast group delete 239.255.0.1 $ cilium-dbg bpf multicast subscriber delete 239.255.0.1 10.244.0.72