Multi-Cloud Networking and the Role of SD-WAN (2020–2025)

Introduction

By 2025, most enterprises are multi-cloud by default. In India, BFSI, IT/ITES, and government sectors deploy workloads across AWS Mumbai, Azure Pune, GCP Delhi, and regional colocation providers. The WAN’s role is no longer to connect a few data centers, but to stitch together multiple public and private cloud fabrics with predictable performance and compliance guarantees.

SD-WAN became the glue that enabled this. This blog unpacks how SD-WAN adapted to multi-cloud requirements from 2020–2025, the emerging standards around multi-segment overlays, and what Indian enterprises learned in practice.

Why Multi-Cloud WAN is Hard

Connecting to one cloud provider is relatively simple: establish a dedicated interconnect (e.g., ExpressRoute, Direct Connect), and extend the WAN overlay. But in a multi-cloud world, enterprises face challenges:

• Fragmented connectivity: Each provider has unique interconnect services, SLAs, and management interfaces.
• Siloed policies: Security and routing policies often need to be duplicated across clouds.
• Performance visibility gaps: Measuring end-to-end latency across segments controlled by different providers is non-trivial.
• Compliance: Indian regulations sometimes mandate local traffic handling, making cross-region routing complex.

SD-WAN Adaptations (2020–2025)

1. Cloud On-Ramps

Enterprises began deploying SD-WAN gateways directly in cloud regions. These “on-ramps” standardized access, enabling policy-based steering regardless of the underlying provider.

2. Multi-Segment Overlays

Drafts in the IETF Routing Area (RTGWG) proposed encapsulating encrypted traffic within transit tunnels (e.g., GENEVE), allowing cloud gateways to forward without decryption. This preserved compliance and reduced re-encryption overhead.

3. Application-Aware Routing

With workloads spread across providers, SD-WAN evolved to recognize app domains and steer flows directly to the right cloud region. For example, collaboration SaaS might go directly to Microsoft’s Mumbai PoP, while analytics workloads route to AWS.

4. Unified Observability

Enterprises demanded end-to-end visibility. By 2024, multi-cloud SD-WAN platforms began exporting unified telemetry — packet loss, latency, jitter — across stitched segments. These fed into enterprise monitoring dashboards for proactive assurance.

Standards and Industry Guidance

• IETF RTGWG Multi-Segment SD-WAN Drafts (2022–2025): Defined encapsulation methods for cross-domain overlays.
• MEF service attribute updates (70.x series): Aligned SD-WAN service definitions with cloud interconnect use cases.
• Cloud-neutral APIs: Allowed WAN controllers to programmatically spin up interconnects across providers.

India’s Multi-Cloud Reality

• Hyperscaler Regions: AWS (Mumbai, Hyderabad), Azure (Pune), and GCP (Delhi) made multi-cloud adoption mainstream.
• Regulation: BFSI and government workloads often required traffic pinning within India, influencing routing policies.
• Local Providers: Many enterprises also used Indian colocation data centers for compliance-sensitive workloads. SD-WAN had to integrate these seamlessly.

Example: A fintech firm in Bengaluru might run core banking apps in a local colocation, analytics in AWS, and collaboration in Microsoft 365. SD-WAN stitched these domains while enforcing policies like “customer data must not leave India.”

Lessons Learned (2020–2025)

• Policy abstraction is key: Without a common policy model, managing multiple clouds quickly became unmanageable.
• Telemetry must be unified: Fragmented dashboards delayed troubleshooting. Enterprises invested heavily in observability pipelines.
• Automation reduces risk: API-driven provisioning lowered errors and sped up deployments.

Future Outlook

• Marketplace-driven: Enterprises will order interconnects across providers via unified portals.
• AI-assisted: Automated systems will suggest routing changes based on real-time performance and compliance rules.
• Compliance-aware by default: APIs will include metadata about jurisdiction and residency to guide policy decisions.

Conclusion

Multi-cloud networking is now the norm, not the exception. SD-WAN’s role is to abstract away complexity, unify policies, and provide observability across domains. For enterprises in India, success depends on combining standards-based overlays with compliance-aware policies tuned to local regulations.

Sources

• IETF RTGWG draft: Multi-Segment SD-WAN
• MEF 70.x service attribute updates
• Cloud interconnect documentation (AWS, Azure, GCP India regions)