Choosing a scalable WAN for many branches: HQ has one router interface left and must connect six existing branches (plus six more soon) economically. Which WAN technology best fits a hub-and-spoke design with many spokes from a single HQ interface?

Introduction / Context:
When many branches need to connect to a single HQ, classic hub-and-spoke WANs used technologies that allowed multiple logical circuits over one physical interface, reducing port costs at HQ.

Given Data / Assumptions:

• One HQ router interface available.
• Six current branches; more expected.
• Goal: economic scalability from one physical port.

Concept / Approach:
Frame Relay supports multiple permanent virtual circuits (PVCs) on a single physical interface using multiple DLCIs. This lets you connect many branch spokes to one HQ hub without additional physical interfaces. (In modern networks, MPLS L3VPN plays a similar role, but classic exam answers emphasize Frame Relay.)

Step-by-Step Solution:

Verification / Alternative check:
Traditional CCNA/CCNP materials present Frame Relay as the scalable choice compared to multiple PPP/HDLC leased lines.

Why Other Options Are Wrong:

• PPP/HDLC: One link per interface per circuit; not scalable with one port.
• ISDN: Dial-up, expensive per minute, not suited for many permanent spokes.
• MPLS L3VPN: Viable modern option, but not among the provided classic solutions; also managed by providers.

Common Pitfalls:
Thinking more physical ports are required; overlooking virtual circuit multiplexing.

Final Answer:
Frame Relay