Defining the Disaggregated Aggregation Router (DAR): A New Blueprint for IP Transport

The Telecom Infra Project's Open Optical & Packet Transport (OOPT) community has published the technical requirements for the Disaggregated Aggregation Router (DAR) — a milestone that marks a significant step toward open, flexible, and future-proof transport networks. Download the document here:

[2026] [OOPT] DAR Technical Requirements_v1.0.4_FINAL.pdf

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Why Does This Matter?

Every time you make a call, stream a video, or connect to the internet from your phone, your traffic travels through a layered network before reaching its destination. One of the least visible — but most critical — parts of that journey is the backhaul: the segment of the network that connects cell towers, homes, and businesses back to the operator's core infrastructure.

Today, the equipment that handles this aggregation layer is largely monolithic and vendor-locked. This means that network operators — mobile carriers, fixed broadband providers — are often tied to a single supplier's hardware and software together, with limited ability to mix and match technologies, innovate independently, or control costs. Upgrading one component can require replacing the whole system. New capabilities from third-party suppliers are difficult or impossible to integrate.

The DAR initiative directly tackles this problem.

What Is a Disaggregated Aggregation Router?

A DAR is a new category of network device designed to sit in the aggregation and backhaul layer of a telecom network — connecting the access layer (where users connect) to the core (where traffic is routed across the internet). What makes it different from today's solutions is its open, disaggregated architecture.

"Disaggregated" means that the hardware and software are intentionally decoupled: the physical box runs on commercial off-the-shelf (COTS) components, while the Network Operating System (NOS) — the software brain of the device — can be supplied by any compatible third party. Operators can swap out hardware or software independently, without affecting the rest of the system. There are no hidden APIs that lock in one vendor, and the hardware is required to support the Open Network Install Environment (ONIE), an industry-standard mechanism that allows any compatible operating system to be installed.

Think of it like a personal computer: you can replace the operating system without buying a new machine, or upgrade the machine without changing the OS. The DAR brings that same philosophy to carrier-grade network infrastructure.

What the Specification Defines

The DAR technical requirements document covers the full stack — hardware, software, management, and security — across a range of deployment sizes and scenarios.

Hardware: Built for Real Networks

The hardware specifications are pragmatic and deployment-focused. DAR platforms are expected to fit in 1 to 3 rack units in standard 19-inch telecom cabinets, support hot-swappable power supplies and fans, and operate across a temperature range of 0 to 45°C to handle diverse installation environments — from air-conditioned data centres to street cabinets.

In terms of raw capacity, the specification defines six hardware size tiers — from XSmall (0.3–1.0 Tbps) all the way up to Large (12 Tbps+) — allowing operators to choose the right fit for each deployment location, whether that's a small street cabinet serving a few hundred subscribers or a major aggregation hub handling tens of thousands.

Interfaces range from 1G up to 400G, including support for 400G-ZR/ZR+ — a coherent optical technology that enables very high capacity over long distances without the need for a separate optical amplification system. This is particularly relevant for operators building compact, cost-efficient transport solutions.

Software: Open and Feature-Rich

On the software side, the DAR must support dual-stack IPv4/IPv6 routing, a comprehensive suite of routing protocols (IS-IS, OSPFv2/v3, BGP-4, and Segment Routing), as well as MPLS label switching with LDP and RSVP-TE signaling.

For service delivery, the platform must support advanced VPN services — L2VPN, L3VPN, and E-VPN — enabling operators to carry mobile traffic, broadband, enterprise, and wholesale services over a common infrastructure. Quality of Service (QoS) capabilities including traffic shaping, policing, and multi-level queuing ensure that different traffic types receive appropriate treatment.

The software requirements are structured around non-mutually exclusive packages, meaning operators can select and license only the capabilities they need — aligned with a pay-as-you-grow model that reduces upfront cost and complexity.

Management and Programmability: Ready for Automation

Modern networks are increasingly managed by software controllers and automation platforms rather than by engineers logging in to configure devices manually. The DAR specification reflects this reality.

The platform must expose its configuration and state through YANG data models and support gNMI (gRPC Network Management Interface) for streaming telemetry — allowing SDN controllers and orchestration systems to monitor and configure the device programmatically in real time. Support for YANG Push enables continuous, subscription-based data export, making it possible to build sophisticated network analytics and automation workflows.

Traditional management protocols (NETCONF, SNMPv3, SSH/CLI) are also required, ensuring compatibility with existing operational toolchains during the transition to full automation.

Zero-Touch Provisioning (ZTP) support means that a DAR device can be deployed in the field and automatically bootstrap itself — downloading its operating system and configuration from a central platform — with no manual on-site intervention required.

Security: Defense in Depth

Security requirements span from the management plane down to the data plane. The specification mandates TACACS+ for operator authentication, full audit logging of CLI commands, SSH with strong encryption, and the ability to restrict management access to defined IP ranges. In the data plane, Unicast Reverse Path Forwarding (uRPF) and DoS protection mechanisms are required, alongside per-subscriber traffic filtering with fine-grained access control lists.

Deployment Scenarios

The DAR is not a one-size-fits-all device. The specification describes multiple deployment models — from a simple inline single device (suitable for smaller deployments) to horizontal scaling with pairs of DARs connected in redundant configurations. A Spine and Leaf architecture using disaggregated whitebox nodes is also highlighted as a scalable approach for larger aggregation deployments.

The services supported cover the full range of modern access technologies: mobile backhaul (connecting 4G/5G base stations), cable aggregation (R-PHY), PON (Passive Optical Networks for fibre-to-the-home), Fixed Wireless Access, and standard Ethernet aggregation for enterprise and residential services. A single DAR platform is expected to be capable of carrying all these traffic types simultaneously.

Requirements Compliance Evaluation (RFI)

With the technical requirements now finalized, TIP is launching a Requirements Compliance Evaluation process — commonly known as an RFI — to enable manufacturers to formally demonstrate that their products meet the DAR specification. Successful submissions will be awarded the TIP Requirements Compliant (Bronze) Badge, providing operators with a clear and trustworthy signal of interoperability.

The RFI timeline is as follows:

• 20 May: RFI announcement and publication of the final Detailed Technical Requirements Document (dTRD)

• 10 June: Deadline for manufacturers to submit Statements of Compliance

• 30 June: Evaluation period concludes

• End of July: Official results and badge allocation
  

Submissions will be treated as TIP PG Staff Confidential, protecting commercially sensitive vendor information throughout the process.

"With the release of these requirements, we are moving beyond theory into industry-wide implementation. The DAR project provides a viable alternative to monolithic solutions, offering the scalability and resilience operators demand for 5G and fixed access. We encourage manufacturing partners to participate in the requirements evaluation process we expect to finalise by the end of H1 2026."

— Kenji Kumaki, Chief Architect, Technology Strategy & Planning, KDDI Corporation, and TIP DOR subgroup co-lead

Get Involved

The DAR specification is a collaborative output from operators including KDDI, Vodafone, Orange, and MTN — representing a broad, global perspective on what the next generation of transport equipment needs to deliver.

If you are a manufacturer looking to certify your solution, or an operator interested in shaping the future of open transport infrastructure, now is the time to engage. Join the TIP OOPT community to access the full technical requirements document and prepare your submission for TIP Exchange: https://www.telecominfraproject.com/oopt.