Boeing Research & Technology This document specifies the operation of IP over tunnel virtual links using Asymmetric Extended Route Optimization (AERO). AERO interfaces use an IPv6 link-local address format that supports operation of the IPv6 Neighbor Discovery (ND) protocol and links ND to IP forwarding. Prefix delegation services are employed for network admission and to manage the routing system. Multilink operation, mobility management, quality of service (QoS) signaling and route optimization are naturally supported through dynamic neighbor cache updates. Standard IP multicasting services are also supported. AERO is a widely- applicable tunneling solution especially well-suited to aviation services, mobile Virtual Private Networks (VPNs) and many other applications.