Under the Hood: Network implementation for World IPv6 Launch

This post details the implementation of Layer 3 DSR for IPv4 and IP6-in-IP6 tunneling for IPv6 to support World IPv6 Launch. It describes the challenges of moving from Layer 2 DSR to Layer 3 DSR, the use of IP-in-IP tunneling to achieve direct server return across L3 domains, and the specific kernel patch required to enable IP6-in-IP6 decapsulation on the fallback device. The post highlights the successful integration of IPv6 as a first-class citizen in their infrastructure, enabling connections from various endpoints.