Which technology encapsulates PPP frames inside Ethernet frames, preserving PPP features such as authentication, compression, and (optionally) encryption?

Introduction / Context:
Broadband last-mile access often needs PPP's features (authentication, accounting) over Ethernet access networks. Different PPP variants adapt PPP framing to various lower layers.

Given Data / Assumptions:

• PPP features desired: authentication (PAP/CHAP/EAP), compression, optional encryption.
• Access media is Ethernet on the customer side.

Concept / Approach:
PPP over Ethernet (PPPoE) wraps PPP frames inside Ethernet frames, allowing ISPs to leverage PPP's session and AAA capabilities over Ethernet distribution. PPPoA instead encapsulates PPP over ATM AAL5, not Ethernet. Plain PPP applies to point-to-point links (serial) without Ethernet framing.

Step-by-Step Solution:

Verification / Alternative check:
Client configuration shows a PPPoE session (PPPoE discovery and session stages), and RADIUS/MFA can be integrated through PPP authentication.

Why Other Options Are Wrong:
PPP: Not inside Ethernet by itself.
PPPoA: Uses ATM, not Ethernet.
Token Ring: Legacy LAN MAC protocol unrelated to PPP encapsulation.

Common Pitfalls:
Confusing PPPoA vs PPPoE due to similar names; always tie the suffix to the underlying medium (A for ATM, E for Ethernet).

Final Answer:
PPPoE