Which statement describes underlay redundancy planning considerations in SD-WAN deployment?

Which statement describes underlay redundancy planning considerations in SD-WAN deployment?

• A. Use diverse transports (MPLS, broadband, LTE/5G) but do not plan for failover.
• B. Ensure path diversity but rely on manual failover only when a link fails.
• C. Consider underlay redundancy by using diverse transports, ensuring path diversity, verifying underlay routing convergence, and designing automatic failover with a consistent MTU.
• D. Use a single transport with no MTU checks.

Answer: (C)

The main concept here is building a robust underlay for SD-WAN that stays available even if individual links fail. To achieve this, you need diverse transports (MPLS, broadband, LTE/5G) so a single outage doesn’t cut connectivity, and you need path diversity so traffic can be steered over alternate routes. It’s also essential to verify underlay routing convergence so, after a change or failure, the control and data planes quickly settle on fresh, correct routes rather than sticking to stale paths. Automatic failover is important so the switch happens without manual intervention, keeping services up with minimal interruption. A consistent MTU across the underlay avoids fragmentation and drops when overlay encapsulation occurs, preserving performance and reliability. This combination—multiple, independent transports; guaranteed path diversity; confirmed rapid routing convergence; automatic failover; and consistent MTU—covers the practical realities of maintaining continuous service in an SD-WAN deployment. The other options miss one or more of these critical factors, such as not planning for failover, relying on manual intervention, or using a single transport with no MTU checks.

The main concept here is building a robust underlay for SD-WAN that stays available even if individual links fail. To achieve this, you need diverse transports (MPLS, broadband, LTE/5G) so a single outage doesn’t cut connectivity, and you need path diversity so traffic can be steered over alternate routes. It’s also essential to verify underlay routing convergence so, after a change or failure, the control and data planes quickly settle on fresh, correct routes rather than sticking to stale paths. Automatic failover is important so the switch happens without manual intervention, keeping services up with minimal interruption. A consistent MTU across the underlay avoids fragmentation and drops when overlay encapsulation occurs, preserving performance and reliability.

This combination—multiple, independent transports; guaranteed path diversity; confirmed rapid routing convergence; automatic failover; and consistent MTU—covers the practical realities of maintaining continuous service in an SD-WAN deployment. The other options miss one or more of these critical factors, such as not planning for failover, relying on manual intervention, or using a single transport with no MTU checks.