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Ubiquiti - IGMP Proxy - Sonos

For Sonos on a dedicated network (VLAN), but to be able to control it from their main network.

Sonos relies heavily on IGMP.

IGMP only works on the same LAN and by design does not work across VLANs.
The solution is using an IGMP-Proxy to repeat the multicast traffic from VLAN the Sonos is on to the main LAN.

IGMP-Proxy Configuration

Prerequisites:

An always-on Unifi Controller.
Unifi Security Gateway.
Known SSH Credentials for the Controller & USG.
mDNS is Enabled.
IGMP Snooping Enabled on VLANs.
UPnP Enabled for only the IoT LAN.
Multicast Enhancements enabled on Wireless Networks.
LAN to WLAN Multicast & Broadcast Data is not blocked.

Create a config.gateway.json file

A config.gateway.json file is needed to be imported onto the Unifi Controller.

NOTE: This file is grabbed by the USG every-time it boots and allows you to run advanced features not yet supported by the Unifi GUI.

By default, the config.gateway.json file does not exist. It has to be created in order to use it.
This config.gateway.json file is placed under the <unifi_base>/data/sites/site_ID directory stored on the Controller.
- The location <unifi_base> will vary depending on your operating system.
- Often, for the Controller and Linux, it is the /usr/lib/unifi/data/sites/default/ directory.

config.gateway.json

{
    "protocols": {
        "igmp-proxy": {
            "interface": {
                "eth1": {
                    "alt-subnet": "0.0.0.0/0",
                    "role": "upstream",
                    "threshold": "1"
                },
                "eth1.10": {
                    "alt-subnet": "0.0.0.0/0",
                    "role": "downstream",
                    "threshold": "1"
                }
            }
        }
    },
    "system": {
        "task-scheduler": {
            "task": {
                "igmpcheck": {
                    "executable": {
                        "path": "/config/igmpcheck.sh"
                    },
                    "interval": "5m"
                }
            }
        }
    }
}

NOTE: The file will need to be edited for your network setup and VLAN ids.

eth1 is the default LAN port on the USG.

eth1 = LAN, eth1.10 = VLAN 10, eth1.200 = VLAN 200
downstream = IoT LAN
upstream = Main LAN

NOTE: If issues are seen in the config, you may need to set the “Upstream” subnet as your WAN and the “Downstream” as your LAN; by changing the interface in the configuration.

The task-scheduler is to make sure the IGMP-Proxy is running every 5 minutes.
- Unifi has a few issues with stopping tasks, and this will correct that.

Import the config.gateway.json file into the Controller

SSH into the Controller, and import the config.gateway.json file into the /usr/lib/unifi/data/sites/default/ directory.

NOTE: There are various ways to import a file.

Consider scp or sftp:

sftp://root@servername/directory

The config.gateway.json file must have unifi:unifi as the owner and group permissions.
```
chown unifi:unifi config.gateway.json
```

igmpcheck.sh

Once the file is in the Unifi Controllers directory after a reboot/ provision of the USG you may notice the IGMP-Proxy begins working. For unknown reasons with Unifi the IGMP-Proxy will suddenly stop running, the igmpcheck.sh script will check to confirm if it is running or not and start the IGMP-Proxy if required.

igmpcheck.sh

#!/bin/bash
pidof igmpproxy >/dev/null
if [[ $? -ne 0 ]] ; then
    echo "restarting igmp-proxy"
    /bin/vbash -ic 'restart igmp-proxy'
fi

NOTE: Once the igmpcheck.sh script is ready it needs to be imported into the USG (not the Unifi Controller) using SSH.

Import the file into the /config/ directory/

Reboot the network

NOTE: Only reboot the network, and not the Unifi Controller.

Test the Sonos

Test the Sonos App on the main LAN.

NOTE: You should see all the functionality of the Sonos app is working.

References

https://help.ui.com/hc/en-us/articles/215458888-UniFi-USG-Advanced-Configuration-Using-config-gateway-json

https://www.nathandare.com/projects/igmp-proxy-configuration-with-sonos

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