The Hybrid IP Reality: Navigating Data Retention & Lawful Request Challenges in the IPv4/IPv6 Era

The enduring complexity of IP legal data requests in network evolution

Telecommunications networks across Europe are in a perpetual state of flux. While the industry's long-term goal is a fully IPv6-native infrastructure, the reality today and for the foreseeable future is a deeply complex, hybrid environment dominated by a mix of legacy IPv4, sophisticated Carrier-Grade Network Address Translation (CG-NAT), and emerging IPv6 deployments.

For Communication Service Providers (CSPs), Internet Service Providers (ISPs) and Mobile Network Operators (MNOs), this technical complexity translates directly into operational risk, particularly regarding Lawful Requests and compliance. When Law Enforcement Agencies (LEAs) or Judicial Authorities make a lawful request for IP data and subscriber identity, accuracy and speed are non-negotiable, especially with the introduction of strictly timed European Production Orders (EPOs).

Today’s IP challenge: Data fragmentation in IP Lawful Requests

The greatest challenge facing Lawful Request teams is not the requests themselves, but the fragmented nature of the data required to answer them correctly.

The CG-NAT bottleneck: The "missing port" dilemma

In IPv4 networks, CG-NAT conserves scarce addresses by forcing thousands of subscribers to share a single public IP address. This creates a critical dependency on precision.

For Law Enforcement, identifying the correct source port is just as vital as the IP address itself. A major operational hurdle arises when the port number is missing from the initial evidence. Without a specific source port and timestamp, a query for a CG-NAT IP address will essentially ask: "Who was using this IP?"  The answer is often a list of thousands of different subscribers who shared that connection simultaneously.

Such a list is useless for intelligence purposes and holds zero evidential value in court. Operators need robust systems that can not only handle these queries but also help LEAs narrow down the scope with a time stamp to ensure only relevant data is handed over.

IP ADDRESS	PORT	DATE	TIME	SUBSCRIBER
82.10.10.1	1024	2025-03-20	02:35-02:40	SUBSCRIBER A

The slow transition: Why the hybrid era is here to stay

IPv6 is often viewed as the solution to the identification problem. An IPv6 address, such as the example below, typically offers a direct line to a subscriber without the obfuscation of NAT:

Example IPv6: 2001:0db8:85a3:0000:0000:8a2e:0370:7334

In this structure, the first part (the Prefix, e.g., 2001:0db8:85a3...) identifies the network and the subscriber's delegation, while the second part (the Interface ID) identifies the device. Generally, LEAs are satisfied with IPv6 capabilities, as it simplifies the process of identifying the customer behind the traffic.

The real challenge

Despite the benefits of IPv6, adoption rates vary wildly and user migration is slow. The majority of internet traffic is still reliant on legacy IPv4 infrastructure. This means the "Hybrid Era", where operators must maintain expensive dual-stack environments and manage complex CG-NAT logs alongside IPv6, will continue for many years to come.

Dynamic address assignments (DHCP/RADIUS) for IP Lawful Requests

In fixed networks, dynamic allocation via DHCP and RADIUS creates a temporary link between an IP address and a physical or logical network identifier (like a MAC address or Circuit ID). This connection must be meticulously tracked, logged, and correlated with the subscriber's billing and CRM data. This triangulation process is complex and often manually intensive.

REX: Unifying traceability and compliance

To overcome these challenges, service providers need an automated, legally validated solution that can stitch together fragmented data sources across the entire hybrid network stack.

This is where REX, Subtonomy's specialized Lawful Request and Data Retention solution, delivers essential operational advantages:

Speed and accuracy: compliance in <30 seconds

The REX mediation platform is designed to instantly ingest, pre-process and cross-reference all network data streams, including CG-NAT logs, DHCP, and IPv6 signaling, to produce a verified subscriber identity and location.

For Lawful Request Managers, this capability is a game-changer:

Guaranteed speed 

Transition from days or hours of manual effort to verified results in under 30 seconds.

Reduced risk 

Automated correlation minimizes human error, ensuring high accuracy and reliability of evidence presented to LEAs.

Case Management and operational ease for IP Lawful Requests

Handling a Lawful Request is not just a technical task; it's a procedural one. REX integrates an intuitive Case Management system to streamline the entire workflow:

End-to-end tracking

Keep detailed audit logs of every request, search, and data handover.

Billing and cost control

Track the effort and resources spent per request for accurate cost recovery and budget management.

IP Lawful Requests for EPOs and E-Codex

The regulatory landscape is constantly evolving. The European Production Order (EPO) creates a unified framework for cross-border data requests with strict deadlines, requiring secure, standardized electronic exchange via e-CODEX.

REX ensures compliance is built in:

Judicial Evidence

Every report is generated with a Chain of Custody to guarantee its evidential value in court.

Regulatory readiness

By maintaining immutable audit logs and standardizing ETSI output formats, REX proactively ensures your operations meet stringent legal requirements and are ready for the automated handling of EPOs via e-CODEX.

Conclusion: The time for automation is now

The hybrid IPv4/IPv6 era demands a strategic shift from manual data retrieval to automated, integrated Lawful Request management. REX provides CSPs, ISPs, and MNOs with the essential toolkit to manage today's complex network data, from CG-NAT logs to randomized IPv6 addresses, and future-proof their operations against evolving EU regulations.

By automating correlation and standardizing case handling, REX transforms compliance from a resource-heavy burden into a secure, fast, and highly accurate operational process.

Ready to secure your compliance?

If you are looking to streamline your Lawful Request handling and ensure robust compliance in a hybrid IPv4/IPv6 landscape, we are here to help. Contact Subtonomy today to discuss your specific network challenges and discover how REX can future-proof your operations.