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SD-WAN: A Strategic Step Toward Zero Trust

The Business Case Challenge

Traditional justifications for SD-WAN adoption have often focused on cost savings versus MPLS or enhanced network features. However, these arguments frequently fall short under scrutiny. The fundamental challenges that limited VPN adoption in enterprise networks – including performance consistency, reliability, and operational complexity – remain relevant despite improvements in internet infrastructure.

The Cost Reality​

Organisations must accept that the transition period will likely increase rather than decrease costs. Running SD-WAN alongside existing infrastructure, maintaining dual skills, and managing the complexity of hybrid operations typically results in higher operational and capital expenses during the transition. The true cost benefits emerge only when zero trust transformation is complete and traditional network security controls can be decommissioned.

The Zero Trust Imperative​

The compelling case for SD-WAN emerges when viewed through the lens of zero trust transformation. Zero trust represents a fundamental shift away from network-based security toward a model where trust is never assumed and must be continuously verified at the application and user level. In this approach, the network location of a user or device becomes irrelevant – whether they’re in an office, at home, or in a coffee shop, the same security controls apply. Every request to access resources must be authenticated and authorised based on identity, device health, and other contextual factors. With zero trust the perimeter melts away and with it the need to maintain it and secure it as the endpoints and applications form their own secure perimeters. Rather than seeing SD-WAN as a network modernisation project, organisations should position it as an essential stepping stone in their journey toward this zero trust model, where secure application access is independent of network location and traditional perimeter-based security controls.

SD-WAN’s Transitional Role​

In this context, SD-WAN serves a crucial transitional function:

Hybrid Security Model

  • Provides network-level authentication and encryption where application-level controls don’t yet exist

  • Enables gradual migration from network-centric to application-centric security

  • Supports coexistence of legacy and modern zero trust-ready applications

Progressive Migration

  • Allows phased decommissioning of traditional network security controls

  • Provides flexibility to maintain stronger network controls for legacy applications

  • Enables immediate zero trust benefits for modern applications

Risk Management

  • Maintains security during transition periods

  • Reduces reliance on network perimeter security

  • Supports graceful migration toward full zero trust implementation

Strategic Implementation​

Success requires:

  • Clear recognition that SD-WAN is a transitional technology

  • Acceptance of increased costs during the transition period

  • Commitment to reducing reliance on network-level security over time

  • Strategic planning for application and endpoint zero trust readiness

The Future State​

As applications and endpoints become zero trust capable, the role of SD-WAN will naturally diminish. Network-level security controls should progressively give way to application-level and endpoint-level security. The end goal is minimal reliance on network-based security, with SD-WAN serving primarily as a transport layer.

This approach provides a pragmatic path forward: leveraging SD-WAN not as a network transformation end-state, but as an enabler of broader zero trust adoption. While the transition period requires investment and acceptance of higher costs, the long-term benefits of zero trust architecture justify this strategic approach. The investment is validated not by immediate network benefits or cost savings, but by its role in facilitating this essential security transformation and the eventual reduction in security complexity and cost once zero trust is fully realised.​​​​​​​​​​​​​​​​