The IETF TRILL Protocol

The IETF TRILL Protocol

This tutorial describes the origin and operation of TRILL (Transparent Interconnection of Lots of Links), an IETF standard that enables a cloud to appear to IP (layer 3) as a single link. Within the cloud, TRILL uses all the standard layer 3 techniques involving multi-pathing and shortest paths,plus some new techniques for multicast distribution. This tutorial explains the limitations of spanning-tree-based layer 2 clouds, as well as the limitations of IP-based interconnection, and why TRILL gives the best of both worlds; the ease of management of layer 2 without the bandwidth limitations. It also contrasts TRILL with other interconnection technologies.