Updates in Android 13
|Introduced split tunnelling||Split tunneling|
The Tethering module shares an Android device's internet connection with other
connected client devices, which can connect to tethering devices over Wi-Fi,
USB, Bluetooth, or Ethernet. This module includes the tethering component (USB,
Wi-Fi access point, Bluetooth, etc.) and its dependencies (interaction with
offloadController). This module is
updatable, meaning it can receive updates to functionality outside of the normal
Android release cycle.
The Tethering module enables OEMs throughout the Android ecosystem to use a single, standard reference implementation that brings the following benefits.
End users get a consistent experience across Android devices and fixes to interoperability issues through module updates.
OEMs can fulfull carrier requirements while also reducing costs for individual customizations (as they don't need different implementations of the same requirements in different ways).
To support split tunneling use cases, a new API is added to Android 13 to specify exclude routes.
Split tunneling refers to the configuration where certain traffic goes through
the VPN while other traffic does not. A common example is where an organization
wants general web surfing, bandwidth-heavy (for example, YouTube, Netflix) or
latency-sensitive applications (for example, Office 365) to bypass the VPN. Before split tunneling was available,
allowed the VPN client to indicate that only some subnets should be routed to it
(include routes). With split tunneling, you have the ability to specify the
inverse: to route all traffic to the VPN, except for specific subnets
The signature of the new split tunneling API is:
public Builder excludeRoute(@NonNull IpPrefix prefix)
CrossDevice, introduced in Android 13, aims to provide cross-device communication technologies using standard protocols. It provides APIs and features for device discovery, authenticated connection, and other cross-device experiences.
- Tighter collaboration with OEM partners. OEMs can integrate their own account key system with CrossDevice implementation instead of needing to use Google's solution.
- More visible implementation of the protocol. The CrossDevice module is open source, providing more visibility into the implementation details and better privacy story for CrossDevice technologies implementation.
CrossDevice module boundary
CrossDevice package format
The main function of this module is included in an APEX package. The resources are packaged in an APK.
CrossDevice depends on the following:
- Proto libraries
CrossDevice customization options
We plan to allow OEMS to customize the UI for half sheet through RRO. There is no plan to customize the functionality.
CrossDevice testing strategy
We plan to add Android Compatibility Test Suite (CTS) tests to verify CrossDevice functionality, and cross device testing into MTS.
eBPF tethering offload
To provide high-speed tethering without replying on hardware offloads, Android 11 provides a tethering software offload solution called eBPF tethering offload for IPv6 download (traffic flowing to tethered device).
From Android 12, this functionality (including the eBPF program code) is entirely provided by the Tethering module, which supports the following:
- IPv6 download (traffic flowing to tethered device)
- IPv6 upload (traffic flowing from tethered device)
- IPv4 TCP/UDP upload and downstream (traffic flowing to/from tethered device)
- eBPF offload
This feature is enabled by default, users
config_tether_enable_bpf_offload configuration to false by RRO.
See Customization for more information.
IPv4 and IPv6 support
The Tethering module supports IPv4 and IPv6 dual stack.
For IPv4 networks, the module sets up network address translation (NAT) and adopts dynamic host configuration protocol (DHCP) for IP address assignment.
For IPv6 networks, the module adopts IPv6 stateless address autoconfiguration (SLAAC) for IP address assignment.
For Android 12 and higher, all the files/folders
packages/modules/Connectivity are in the Tethering module scope.
For Android 11 and lower, the Tethering module has
the following Android 10 files in
The Tethering module (
com.google.android.tethering) is in APEX format and is
available for devices running Android 11 or higher.
From Android 12, the
ConnectivityService code that
implements the central component of L3+ connectivity is added to the Tethering
APEX. The scope of Tethering expands into a Connectivity module.
The Tethering module has the following dependencies:
- Public and system API methods in the system server
- Stable AIDL IPCs interface with the system server
tetheroffloadHIDL (defined in
- DHCP server (part of the Network Stack module)
The Tethering module doesn't support customization.
The Android Compatibility Test Suite (CTS) verifies functionality of the Tethering module.