Huawei SD-WAN provides flexible Internet access options based on enterprise architecture and policies:

A. Centralized Internet access : Internet traffic from branches is sent to HQ or data center before being forwarded to the Internet

C. Local Internet access : Internet traffic is directly forwarded at the branch (also called DIA — Direct Internet Access)

D. Hybrid Internet access : Combines centralized and local Internet access based on application type or policy

B. Remote Internet access is not a standard Huawei-defined mode in this context.

In Huawei's data center network architecture, an underlay network refers to the physical infrastructure comprising switches, routers, and other network equipment (e.g., VAS devices), responsible for basic IP connectivity. This supports statement B.

The overlay network is logically built on top of the underlay and uses tunneling protocols such as VXLAN (MAC-in-UDP) to encapsulate Layer 2/Layer 3 service traffic. This encapsulation ensures transparent delivery of packets across IP underlays. This supports both C and D.

Statement A is incorrect: even when using an overlay, the underlay still requires routing protocols (like OSPF, BGP) or static routes to ensure IP reachability between VXLAN Tunnel Endpoints (VTEPs). Overlay tunnels ride on top of this IP connectivity.