Is End-to-End Connectivity the Right Goal?

Why It Matters

Restoring end‑to‑end connectivity with IPv6 can reduce unnecessary complexity, lower costs, and foster innovation, while challenging entrenched NAT‑driven business models that limit open internet participation.

Key Takeaways

• IPv6 aims to restore end‑to‑end connectivity lost with NAT.
• NAT arose from IPv4 address scarcity and broadband growth.
• Industry profits from limited connectivity, conflating NAT with security.
• IETF resists NAT standards to preserve end‑to‑end principle.
• Practical networks can operate without NAT, but adoption remains low.

Summary

The episode tackles a foundational design question: should the internet’s architecture prioritize end‑to‑end connectivity, especially as IPv6 promises to revive the principle that IPv4 lost to network address translation (NAT)? Hosts Ed Horley, Nick Baralio, and Tom Coffin trace the evolution from the early, fully public IPv4 space to the era of address conservation, broadband proliferation, and the rise of NAT as a de‑facto security and management tool.

They argue that NAT was born out of two forces: the need to stretch a limited IPv4 pool and the desire of many broadband providers to hide consumer devices behind a single address. Over time, the industry bundled NAT with firewall functions, creating a market that profits from restricted connectivity. The hosts note that the IETF has historically defended the end‑to‑end ideal, rejecting NAT‑centric extensions for IPv6, yet the practical reality shows many operators still rely on masquerading for convenience and perceived security.

Memorable moments include Baralio’s declaration, “I’ll die on that hill,” defending pure end‑to‑end design, and Coffin’s reference to a 12‑year‑old talk demonstrating high‑performance data centers operating without any middlebox or firewall. The discussion also highlights the tension between standardization—preventing a “wild‑west” of proprietary NAT implementations—and the industry’s reluctance to abandon a model that has become financially lucrative.

The takeaway for network architects and policymakers is clear: while IPv6 offers the address space to restore true end‑to‑end communication, the entrenched NAT ecosystem and its security narrative may hinder adoption. Re‑evaluating NAT’s role, encouraging transparent standards, and educating operators on viable NAT‑free designs could unlock the innovative potential the internet’s original design intended.

Original Description

One of the early design principles of the Internet was end-to-end connectivity: that is, every device on the Internet would be publicly addressable, and every device could share its resources or provide services. That design principle wasn't achieved with IPv4 for a variety of reasons (including address scarcity, and many network owners not wanting endpoints to be publicly reachable without mediation).

On today's episode, Ed, Nick, and Tom re-examine the end-to-end connectivity principle, which many IETF IPv6 stalwarts hold up as the standard that should be strived for. They discuss the history of the principle, its eventual erosion in IPv4, and whether the IETF’s adherence to the end-to-end principle in IPv6 is realistic.

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