What is technical architecture?
Technical architecture is the layer of enterprise architecture that defines which technical infrastructure (networks, servers, storage, platforms, middleware and security facilities) an organisation needs and which principles and standards govern how it is built, so that applications, data flows and business processes run reliably, securely and manageably. It is not a single system but a coherent set of choices and agreements about the technology underneath every other layer. In TOGAF this layer is called Technology Architecture, in ArchiMate the Technology Layer, and in the Dutch government reference architecture NORA the IT infrastructure layer.
Technical architecture forms the underlying layer on which application architecture, information architecture and business architecture are built.
🧠 What falls under technical architecture?
| Component | Description | Examples |
|---|---|---|
| Network infrastructure | Connections within and between sites | LAN/WAN, VLANs, routers, firewalls, load balancers |
| Compute and storage | Processing power and data storage | Servers, workstations, SAN/NAS, backup facilities |
| Platforms and virtualisation | Layers that separate applications from hardware | Hypervisors, virtualisation, containers with Docker and Kubernetes |
| Cloud | Consumed infrastructure and platform services | IaaS, PaaS and SaaS in the cloud |
| Middleware and integration | Message traffic between systems | ESB, API gateways, message brokers |
| Security facilities | Generic security building blocks | Firewalls, proxies, identity providers, IAM |
| Operations and monitoring | Insight into availability, performance and incidents | Monitoring, central logging, CMDB |
A technical architecture describes these components at three levels: principles (for example “standardise on a limited number of platforms”), standards and catalogues (which products, versions and protocols are allowed) and models (how the components fit together, which zones exist and where applications run).
🔁 How does technical architecture relate to the other layers?
| Architecture layer | Link with technical architecture |
|---|---|
| Business Architecture | Processes set requirements for availability, speed and scalability |
| Information Architecture | Data storage, access, retention periods and security must be supported technically |
| Application Architecture | Applications run on the platforms and networks that the technical architecture describes |
Requirements flow downwards: a process that must run 24/7 needs applications with failover and, underneath, redundant servers and network paths. Conversely, the technology limits what the higher layers can promise. Without a stable technical architecture, no other layer can function reliably.
🧩 How do TOGAF and ArchiMate describe the technology layer?
TOGAF (currently the TOGAF Standard, 10th Edition, published in 2022) develops technical architecture in Phase D (Technology Architecture) of the Architecture Development Method. In this phase the architect selects reference models and viewpoints, describes the current (baseline) and desired (target) technology, performs a gap analysis and records the result in the Architecture Definition Document. New technology building blocks are defined in detail during this phase.
ArchiMate models the Technology Layer with elements such as node, device, system software, communication network and path. Since ArchiMate 3.0 (2016) there are also physical elements: equipment, facility, distribution network and material. They let you put a pumping station, a production line or a power distribution system in the same model as servers and networks. In ArchiMate 3.2 (2022) these physical elements were brought into the Technology Layer chapter. Precisely these physical elements make ArchiMate suitable for describing OT convergence in a single architecture model.
🏛 What role does technical architecture play in the Dutch government?
| Reference architecture | Role of technical architecture |
|---|---|
| NORA | The IT infrastructure layer of the five-layer model: networks, platforms and generic facilities such as Diginetwerk, hosting and logging |
| GEMMA | The base architecture for municipalities contains a technical architecture alongside principles, business architecture and information architecture |
| WILMA | The Infrastructure layer describes the generic technical facilities for the water authorities |
| MARIJ | The historic central government architecture followed the same layering; MARIJ was succeeded by the EAR and the RORA |
For organisations that fall under the BIO, the Dutch government information security baseline, technical architecture is where security measures such as network separation, logging and backup are put into practice.
🏭 What is different about technical architecture in OT?
Operational technology (OT) has different priorities from office IT. The full structure of process automation is covered in OT Architecture; technical architecture supplies the generic infrastructure for it, such as networks, servers, virtualisation and management facilities.
| Aspect | IT infrastructure | OT infrastructure |
|---|---|---|
| Priority | Confidentiality and integrity | Availability, safety and determinism |
| Lifespan | Often 3–5 years | Often 15–25 years, including legacy systems |
| Patching | Monthly, automated | Only in maintenance windows, after vendor approval |
| Network layout | Functional VLANs | Levels of the Purdue Model, zones and conduits |
| Connection to IT | Direct | Through an IDMZ or a data diode |
Typical OT applications are SCADA systems with redundant servers and serial and TCP/IP links, remote I/O networks with industrial switches, modems and edge devices, industrial networks with VLAN structures and QoS for time-critical traffic, and IT/OT connections through OPC UA or MQTT. In OT, availability and determinism are often more important than scalability or flexibility.
🔐 How do you build security into the technical architecture?
- Security by Design - security is part of the network and server design, not a layer added on top
- Frameworks - BIO, ISO 27001 and, for OT, IEC 62443; under the Dutch Cybersecurity Act (in force since 15 August 2026) appropriate security of network and information systems is a duty of care
- Segmentation - network segmentation according to the zones and conduits model
- Baseline measures - Hardening, patch management and identity and access management (IAM)
- Detection and recovery - monitoring for anomaly detection, logging for forensic investigation and a tested disaster recovery plan
🔧 How do you draw up a technical architecture?
- Inventory the current situation - record all components and dependencies in a CMDB or asset register.
- Translate requirements from the higher layers - which processes and applications need which availability, recovery time (RTO) and maximum data loss (RPO)?
- Formulate principles and standards - for example “virtualise unless”, “one monitoring platform” or “no direct IT-OT connections”.
- Design the target architecture - zones, platforms, redundancy and integration patterns, modelled in ArchiMate.
- Plan a migration path - close the gap step by step, aligned with the lifecycle management of existing systems.
- Embed it in operations - assess changes through change management and automate where possible with Infrastructure-as-Code.
In step 2 it helps to translate availability into concrete downtime:
| Availability | Maximum downtime per year | Typical use |
|---|---|---|
| 99% | approx. 3.7 days | Test environment, non-critical reporting |
| 99.9% | approx. 8 hours 46 minutes | Office applications, intranet |
| 99.99% | approx. 53 minutes | ERP, MES, central SCADA server |
| 99.999% | approx. 5 minutes | Process control, network core with high availability |
Also document all dependencies: this is crucial for business continuity and incident response.
❓ Frequently asked questions
What is the difference between technical architecture and infrastructure?
Infrastructure is the collection of actual hardware, networks and platforms. Technical architecture is the design and framework above it: which infrastructure is needed, which principles and standards govern how it is built, and how the parts fit together.
What is the difference between technical architecture and OT architecture?
Technical architecture is a layer of enterprise architecture that describes the generic technology for the whole organisation. OT architecture specifically describes the structure of process automation, from sensor and PLC to SCADA and the connection with IT, and uses the networks and platforms defined in the technical architecture.
Which TOGAF phase covers technical architecture?
In TOGAF, technical architecture is developed in Phase D, Technology Architecture, of the Architecture Development Method. That phase describes the current and target technology, analyses the gaps and records the outcome in the Architecture Definition Document.
How do you model technical architecture in ArchiMate?
In ArchiMate you use the Technology Layer with elements such as node, device, system software, communication network and path. For OT environments you add the physical elements equipment, facility, distribution network and material, so that machines and installations sit in the same model as servers.
Who is responsible for the technical architecture?
Usually an infrastructure or domain architect draws up the technical architecture, under the direction of the enterprise architect. In organisations with OT, that architect works closely with the person responsible for OT, because choices about networks, virtualisation and patching directly affect the availability of production processes.
Why does technical architecture matter for cybersecurity?
Technical architecture determines where network boundaries lie, how systems are hardened and patched, and where logging takes place. Measures from the BIO, ISO 27001 and IEC 62443 only really work once they are anchored in the technical architecture.
📌 In summary
Technical architecture is the foundation of a digital organisation: it defines which networks, platforms and security facilities are needed and which principles govern how they are built.
Technical architecture is the bottom layer of enterprise architecture and is worked out in TOGAF Phase D and the ArchiMate Technology Layer. In the Dutch government it aligns with NORA, GEMMA and WILMA. In OT environments the priorities shift to availability, long lifespans and strict separation between IT and OT. Without stable, secure and scalable infrastructure, processes, information and applications cannot function, in IT and OT alike.