Introduction
Preferred Network Interface(PNI) is a feature introduced in RDK to avoid the confusion related to network connectivity and switch seamlessly between different interfaces. Currently it is meant for WiFi and ethernet interfaces.
Background
For RDK client profiles, the network connectivity options are usually two, ethernet and WiFi.Ethernet is the preferred interface over WiFi, but the option to choose interface is exposed to user. PNI logic is encoded in /lib/rdk/pni_controller.sh
By default if ethernet interface is active and connected, WiFi interface will be disabled. This behavior can be altered using environmental settings.
Features
- Ability to switch between interfaces seamlessly
- Ability to verify the connectivity options
systemd services involved
pni_settings_loader.service
This service is managed by systemd.This is mostly used to load the persisted data from previous runs.
pni_controller.service
This services is controlled by netsrvmgr service. This is invoked every time a network interface status is changed. Possible scenarios include, but not limited to
- Ethernet connect/disconnect
- invoking setInterfaceEnabled API
- Wifi endpoint connect/disconnect.
Switching between interfaces
If ethernet cable is out, nlmon service will trigger the link change event, which results in restarting the pni_controller.service. This result in wifi being configured:
- Layer 1 - ifconfig wlan0 up
- Layer 2 - connection to SSID (after WifiInterfaceState 1 signaled to netsrvmgr to turn on wifihal and wpa_supplicant)
- Layer 3 - IP configuration (via DHCP mostly for IPv4 and SLAAC for IPv6)
Similarly when ethernet cable is connected, netsrvmgr is notified, pni_controller.service is restarted. All wifi related components, including wpa_supplicant service is deactivated.
Environment Settings
The following variables can be used to alter the functionality of PNI. These are defined in pni_controller.service
- CONFIG_DISABLE_PNI
- determines whether PNI is enabled in the device. - CONFIG_DISABLE_CONNECTIVITY_TEST
- determines whether a connectivity test needs to be done after network is established - CONFIG_ALLOW_PNI_TO_DISABLE_WIFI
- determines whether PNI can disable wifi interface altogether or remove route and ip address information alone.
RDK Feature Control(RFC) settings
The following RFC variables can be used to alter the network selection logic of PNI.
Device.DeviceInfo.X_RDKCENTRAL-COM_RFC.Feature.PreferredNetworkInterface
- Use this RFC to set WiFi as default interface. By default Ethernet is the default interface.
Device.DeviceInfo.X_RDKCENTRAL-COM_RFC.Feature.Network.AllowDisableDefaultNetwork
- Use this to disable interface irrespective of whether the interface is the active interface or not.
If this RFC is not enabled, you can only disable passive interfaces.
Connectivity test options
After establishing network connectivity , PNI can verify the connectivity status of the network. It does by reaching out to endpoints specified in /opt/persistent/connectivity_test_endpoints if available, otherwise defaulting to "google.com espn.com speedtest.net" websites.
References
RDK-14208 (1.0)
RDK-29489 (2.0)
Networking Details
