HangZhou H3C Co. Limited HangZhou H3C Co. Limited Hewlett-Packard Co. Hewlett-Packard Co. TRILL is a key technology for large-scale layer 2 networking within a data center, TRILL over WAN_(ToW) provides a scalable and simple solution that interconnect multiple TRILL networks to form a single TRILL domain using the currently deployed enterprise or service provider networks. This document provides an overview of this solution.