By The JDneer in android — 19 Sep 2025

Android Adds DHCPv6 Prefix Delegation - What It Means & Why It Matters

After years of requests and debates among network engineers, Google has announced that Android is now shipping support for DHCPv6 Prefix Delegation (PD).

Photo by Denny Müller / Unsplash

Introduction

After years of requests and debates among network engineers, Google has announced that Android is now shipping support for DHCPv6 Prefix Delegation (PD). According to the Android Developers Blog, DHCPv6 PD support is expected to roll out to most devices running Android 11 and above before the end of the year via a Google Play System Update.

This change is significant for both enterprise/ISP setups and advanced home networks. In this article, we’ll dig into what DHCPv6 PD is, why Android’s support is a big deal, what caveats remain, and what to plan for going forward.

What is DHCPv6 Prefix Delegation?

DHCPv6 (Dynamic Host Configuration Protocol for IPv6) is the equivalent of DHCP for IPv4 but designed for IPv6 networks. One of its features, Prefix Delegation (PD), allows a DHCPv6 server (often operated by an ISP) to assign an entire IPv6 prefix (e.g., /56, /60, /64 etc.) to a downstream router or device. That downstream router can then use that delegated prefix to subnet locally (e.g., for LANs or multiple segments), handing out IPv6 address blocks to devices under it, either via SLAAC or other mechanisms.

Until now, Android devices did not support DHCPv6 PD as clients. They primarily relied on SLAAC (Stateless Address Autoconfiguration) and router advertisements (RAs) for configuration. This has been a longstanding gap, especially for environments where automated and stateful management of IPv6 addressing is needed.

What’s New: Android’s DHCPv6 PD Support

According to the official announcement:

Devices running Android 11 and newer will get support for DHCPv6 PD via a Google Play System Update.
The rollout is expected before the end of 2025.
Google states this update complies with both RFC 8415 (standard DHCPv6 behavior) and RFC 9762 (which introduces a “P flag” for Prefix Information Options in Router Advertisements).

Why This Matters

For ISPs, Enterprises, and Managed Networks

Better Automation and Uniformity: Android devices can now request a delegated prefix rather than relying only on SLAAC or fixed /64’s.
Address Space Flexibility: Delegated prefixes allow flexible subdivision among networks—useful for campuses, branching sites, or mesh networks.

For Home Labs & Tech Enthusiasts

Improved Router/RA Setups: With RA enhancements (including the new prefix-flag defined in RFC 9762), routers can better signal what’s expected, making Android clients behave more predictably.
Enhanced Enterprise & Developer Compatibility: Many tools, VPNs, and internal services require stateful address assignment or delegated prefixes; Android support makes integration smoother.

For General Users

In many typical Wi-Fi or cellular usage scenarios, changes may not be visible. But in any network that supports PD + RA prefix-flag, configuration and reconfiguration under changes should be more seamless and robust.

Limitations & Things to Watch Out For

Rollout Pace & Device Eligibility
Only Android 11+ will receive support via Google Play System Update. Some devices may lag behind.
ISP/Network Support Required
The upstream network/router must support DHCPv6 PD and the RA “P flag” per RFC 9762. Without both, the full functionality may not work.
Prefix Changes & Reliability
Delegated prefixes may change (e.g. on network reattachment). Applications must handle this gracefully.
Security & Privacy
Delegated prefixes can introduce longer-lived identifiers than temporary addresses. IPv6 privacy mechanisms and network policies should be considered.
Remaining Gaps
Some router firmware or network gear may not yet support RFC 9762; behaviors around DNS, fallback, and router advertisement consistency remain to be fully tested.

What About Prefix Sizes?

Google has not yet specified exactly which prefix sizes Android will request or accept. Based on current IPv6 deployment practices:

/56 and /60 are commonly used by ISPs for customer delegations.
/64 is standard for LAN segments and is almost certainly supported.
Larger delegations like /48 may be usable when upstream networks permit.

Standards such as RFC 8415 allow a range of prefix lengths; recent implementations and ISPs typically offer from /48 up to /64 depending on scale.

New RFC Requirement: Prefix-flag in RA & RFC 9762

As noted by Daryll Swer of daryllswer.com, in discussion on this topic:

“But you need new RFC support for this to work properly
It’s called Prefix-flag in RA
RFC 9762”

RFC 9762, “Using Router Advertisements to Signal the Availability of DHCPv6 Prefix Delegation to Clients”, defines the P flag in the Prefix Information Option (PIO) of IPv6 Router Advertisements, which signals to clients that the network supports PD.

Network operators should ensure their router advertisements support RFC 9762 so that Android’s DHCPv6 PD support functions as expected.

Practical Implications & Recommendations

Audit your routers & firmware: Make sure your network gear supports both DHCPv6 PD and the RA prefix-flag (RFC 9762).
Test Android devices in PD+RA environments: Observe behavior under prefix changes.
Document your IPv6 architecture: Include notes about PD, RA behavior, and prefix size policies.
Watch for updates from ISPs: Many may need to upgrade firmware or configuration to support these new RFCs.

Broader Context: IPv6 Progress & Android’s Stance

Previously Android did not have full DHCPv6 PD support; it relied more heavily on SLAAC and router advertisements. With this addition, Android is aligning more closely with modern IPv6 best practices, including compliance with RFC 8415 and now RFC 9762.

These developments reflect a maturing IPv6 ecosystem, in which both client and network infrastructure are being updated to support more robust address delegation, signaling, and management.

Conclusion

Android’s support for DHCPv6 Prefix Delegation, together with RFC 9762’s RA prefix-flag support, represents a significant step forward. While much of this change will be invisible for many users, for network administrators, power users, and ISPs this opens up better automation, stability, and flexibility.

As always, success depends on the full ecosystem: device software, network hardware, ISP infrastructure, router firmware, and proper configuration. With all these pieces coming together, the gap in IPv6 address delegation workflows is finally closing.