VPN concept: What term best describes creating private networks across the Internet that provide privacy and can tunnel non-TCP/IP protocols?

Introduction / Context:
This item distinguishes the general concept of Virtual Private Networks (VPNs) from specific technologies. A VPN is a method of using shared networks to provide private connectivity with encapsulation and security.

Given Data / Assumptions:

• The network is the public Internet or other shared IP backbone.
• Goal: privacy and the ability to tunnel traffic, including potentially non-TCP/IP protocols depending on encapsulation.

Concept / Approach:
VPN is a broad term that encompasses technologies allowing creation of logical private links over public infrastructure. Features include tunneling (encapsulation), authentication, integrity, and often encryption. Implementations may use IPSec, SSL/TLS, GRE combined with IPSec, or MPLS-based L3VPN/L2VPNs, among others.

Step-by-Step Solution:

Verification / Alternative check:
Common deployments label SSL remote-access and IPSec site-to-site solutions collectively as VPNs; GRE tunnels can carry non-IP protocols over IP and are often protected by IPSec.

Why Other Options Are Wrong:
IPSec: A specific standard protocol suite, not the umbrella concept.
HDLC/Cable/xDSL: Access technologies, not privacy/tunneling solutions across the Internet.

Common Pitfalls:
Confusing IPSec (implementation) with VPN (service/concept). The question wording favors the concept.

Final Answer:
VPN