A speculative alternate history imagines what the Internet would look like if, in 1993, the IPng working group had chosen to extend IPv4 with 128-bit addresses (IPv4x) rather than designing IPv6 as a clean-break replacement. In this parallel universe, IPv4x packets remain backward-compatible with existing routers by keeping the version field at 4 and tucking the extra 96-bit 'subspace' into the packet body, enabling gradual adoption without a flag day. The piece traces this fictional timeline from 1993 through 2026, covering DNS/DHCP updates, MIT's early deployment, the peer-to-peer explosion, and eventual near-universal adoption. The author then reflects on what IPv6 actually fixes that IPv4x would not have (cleaner autoconfiguration, simpler routing, better multicast), concluding that IPv6's longer road leads to a better destination. The piece ends by revealing the thought experiment was a setup to introduce SixGate, the author's real proposal for helping IPv4 users reach IPv6 services via special SRV records in ip6.arpa.

14m read timeFrom owl.billpg.com
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