LinkedIn Comcast LinkedIn The Internet is not one network, but rather a collection of networks. The interconnected nature of these networks, and the nature of the interconnected systems that make up these networks, is often more fragile than it appears. Perhaps "robust but fragile" is an overstatement, but the actions of each vendor, implementor, and operator in such an interconnected environment can have a major impact on the stability of the overall Internet (as a system). The widespread adoption of IPv6 could, particularly, disrupt network operations, in a way that impacts the entire system. This time of transition is an opportune time to take stock of lessons learned through the operation of large-scale networks on IPv4, and consider how to apply these lessons to IPv6. This document provides an overview of the design and architectural decisions that attend IPv6 deployment, and a set of IPv6 requirements for routers, switches, and middleboxes deployed in IPv6 networks. The hope of the editors and contributors is to provide the necessary background to guide equipment manufacturers, protocol implementors, and network operators in effective IPv6 deployment.