> was a stupidly complex beast compared to IPv4 How are you measuring complexity? IPv4 started simple, but had a lot of extensions (literally header "options"

> was a stupidly complex beast compared to IPv4 How are you measuring complexity? IPv4 started simple, but had a lot of extensions (literally header "options") to fix and mitigate various issues and underspecified behaviour. IPv6 started more complex, but had a lot of those shortcomings addressed from decades of experience in the real world. In the Linux kernel, IPv6 is actually implemented with fewer lines of code than IPv4 (as of 6.12.19, IPv4 = 82kloc, IPv6 = 58kloc).