A traditional WAN does not rely on the same overlay, controller-based policy distribution, tunnel encapsulation, or centralized abstraction model used by SD-WAN. Because of that, one valid benefit is lower data plane overhead. SD-WAN commonly adds encapsulation, encryption, tunnel metadata, and policy-based forwarding logic across WAN edge devices, which creates additional processing and packet overhead compared with a more direct traditional WAN path. The second benefit is lower control plane abstraction. Traditional WAN routing is usually built directly with protocols such as OSPF, EIGRP, BGP, static routing, MPLS VPN routing, or other conventional mechanisms. That makes the control-plane operation less abstracted than SD-WAN, where controllers calculate, distribute, and enforce policies across WAN edges. Options A, C, and E are stronger SD-WAN benefits. SD-WAN is designed to standardize policy, simplify operational management through centralized control, and improve application-aware path selection or failover. Traditional WAN can be simpler in small environments, but it does not inherently provide comprehensive standardization or faster fault detection. References/topics: ENCOR Architecture, WAN design, SD-WAN overlay, control plane abstraction, data plane encapsulation overhead.
