A Sonos Inter-VLAN Relay (sonos-relay) may be necessary when Sonos devices are on a separate VLAN from their controllers. This repository documents the deployment of a multicast-relay on a Raspberry Pi dedicated for this purpose.

Guidance given here helps to avoid networking problems with Sonos devices.

It is best to create a VLAN dedicated exclusively to Sonos devices. Wire all Sonos devices into this VLAN. Because they are wired, they do not mesh wirelessly (using SonosNet) which, if not handled carefully with the right STP configuration, can create disasterous network loops.

Do not use the extra port in the embedded switches of some Sonos devices.

Control of Sonos devices is done using the Sonos application on a phone or Windows machine. Since the Sonos devices have been isolated on their own separate VLAN, such communication is not possible without some remediation.

To solve some of this problem, one can turn on IGMP Snooping and Multicast DNS (mDNS) between the necessary VLANs on a Ubiquiti Dream Machine (UDM). Unfortunately, the UDM does not also support a necessary UPnP SSDP relay capability.

Fortunately, deployment of a multicast-relay solves this problem. It seems that this used to be deployable on a UDM in a Docker container. That does not seem to be the case now. A similar deployment might be done on a capable NAS but that would invite some exposure/risk from these VLANs. Instead, it seems best to deploy a dedicated device for this purpose.

This describes the installation from a Fedora Linux machine. The same results can be achieved otherwise.

Download a Raspberry Pi OS image. Raspberry Pi OS Lite will suffice.

Use

gnome-disks

to identify where the media is. For example,

media=/dev/sda

Write the downloaded image to the media

xzcat 2023-12-05-raspios-bookworm-arm64.img.xz | sudo dd obs=1M oflag=direct of=$media

Resize the rootfs to consume all free space (using gnome-disks). Mount bootfs and rootfs.

Enable ssh on boot.

sudo touch /run/media/$USER/bootfs/ssh

Enable pi account login by replacing its impossible password hash ('!') with a known one (e.g. yours from /etc/shadow).

sudo vim /run/media/$USER/rootfs/etc/shadow

Unmount bootfs and rootfs using gnome-disks.

Configure the Raspberry Pi's switch port so that its default VLAN is that of the Sonos devices. Add the tagged VLANs of the Sonos controllers.

Attach the Raspberry Pi to the network and start it.

Optionally, give it a reserved DHCP address and DNS name (e.g. sonos-relay.home.arpa).

Because the routing configuration of the Raspberry Pi will change during the configuration described here, it is best to (temporarily?) place the machine you will be accessing it from on the same VLAN (by default or with a VLAN tagged interface).

Login

ssh [email protected]

Set timezone. For example,

timedatectl list-timezones
sudo timedatectl set-timezone America/Los_Angeles

Git sonos-relay

# git clone [email protected]:rtyle/sonos-relay
git clone https://github.com/rtyle/sonos-relay
(cd sonos-relay; git submodule update --init --recursive)

Configure the VLAN interfaces. For each tagged VLAN,

nmcli con add type vlan con-name $name dev eth0 id $id ip4 $ip

Where $name is the name of the VLAN, $id is its VLAN ID and $ip is its IPv4 CIDR address to this VLAN.

Install dependencies

sudo apt install python3-netifaces

sudo python /home/pi/sonos-relay/multicast-relay/multicast-relay.py --interfaces $(nmcli con | tail -n +2 | awk '{print $NF}' | grep eth0) --noMDNS --foreground --verbose

Enable the service. It will start automatically on reboot.

sudo systemctl enable /home/pi/sonos-relay/sonos-relay.service

Start it now

sudo systemctl start sonos-relay

Status

systemctl status sonos-relay

Follow verbose logging (add --verbose to unit file)

journalctl -u sonos-relay -f