This document presents an architecture for an IPv6 Multi-Link subnet that is composed of a high speed powered backbone and a number of IEEE802.15.4e TSCH wireless networks attached and synchronized by Backbone Routers. The TSCH schedule can be static or dynamic. 6TiSCH defines mechanisms to establish and maintain the routing and scheduling operations in a centralized, distributed, or mixed fashion. Backbone Routers perform proxy Neighbor Discovery operations over the backbone on behalf of the wireless devices, so they can share a same subnet and appear to be connected to the same backbone as classical devices