IP Version 6 Addressing Architecture
Embed This Widget
Add the script tag and a data attribute to embed this widget.
Embed via iframe for maximum compatibility.
<iframe src="https://ipfyi.com/iframe/entity//" width="420" height="400" frameborder="0" style="border:0;border-radius:10px;max-width:100%" loading="lazy"></iframe>Paste this URL in WordPress, Medium, or any oEmbed-compatible platform.
https://ipfyi.com/entity//Add a dynamic SVG badge to your README or docs.
[](https://ipfyi.com/entity//)Use the native HTML custom element.
R. Hinden, S. Deering · 2006-02
Abstract
RFC 4291 defines the addressing architecture for IPv6, specifying the types of addresses (unicast, anycast, multicast), their formats, and their assignment rules. It establishes the 128-bit address space notation, address scopes, and the special address ranges that IPv6 implementations must recognize.
Why This RFC Matters
As IPv4 exhaustion became a certainty, RFC 4291 provided the addressing foundation for IPv6's 128-bit address space — large enough to assign unique addresses to every atom on Earth's surface many times over. The RFC introduced important innovations over IPv4 addressing: link-local addresses that enable automatic neighbor discovery, mandatory multicast replacing broadcast, and the elimination of broadcast entirely. The loopback address (::1), the unspecified address (::), and the structure of globally routable addresses all originate here. RFC 4291 is the definitive reference for anyone implementing or operating IPv6 networks.