Huawei Huawei Intel Labs Hewlett-Packard Cumulus The IETF TRILL (TRansparent Interconnection of Lots of Links) protocol is a solution for least cost transparent frame routing in multi-hop networks with arbitrary topologies and link technologies, using IS-IS (Intermediate System to Intermediate System) link-state routing and encapsulation with a hop count. IS-IS supports multiple topology routing. This document specifies a TRILL data plane encoding and procedures to make use of such routing.