Explain SD-WAN

Question 1

What is the business drivers of SDWAN?

Answer 1

Traditional WAN architectures based on MPLS models struggle with cloud adoption, SaaS usage, and the need for direct internet access.

SD-WAN addresses these challenges by enabling intelligent path selection, centralized policy control, and improved application performance across hybrid WAN links.

Question 2

Define SD-WAN Clearly?

Answer 2

SD-WAN is a software-defined overlay that uses centralized control and orchestration to manage WAN traffic across multiple underlays like MPLS, broadband, and LTE. It uses application-aware routing, encrypted tunnels.

Question 3

Describe the Key SDWAN Architecture Components?

Answer 3

• vEdge / cEdge: Data-plane devices deployed at branch or campus.
• Controllers: Orchestrator, vSmart (policy), vBond (authentication).
• Overlay: IPsec/GRE tunnels over underlays like MPLS/INET.
• Transport: MPLS, Broadband, LTE — abstracted from applications.

Question 4

Highlight Your SDWAN Design Thinking?

Answer 4

• Hub-and-Spoke vs. Full-Mesh: Decide between hub-and-spoke or full-mesh overlay designs.
• DIA Placement: Plan where to place Direct Internet Access (DIA) for optimal performance.
• Security Integration: Integrate with on-prem firewalls or cloud-delivered SSE (Security Service Edge).
• QoS & Traffic Engineering: Design QoS and traffic engineering policies to prioritize critical applications.
• Controller-Based Policies: Use controller-based policy models to consistently enforce network intent.

Question 5

Example of SDWAN projects?

Answer 5

I’ve deployed Cisco SD-WAN (Viptela) for a retail customer with 300+ branches. We replaced MPLS with dual broadband links, enabled DIA with URL filtering, and implemented app-aware routing to send critical traffic via preferred paths. We achieved a 40% reduction in circuit cost and improved Office365 latency.