Challenges and Opportunities in the Design of TRILL: A Routed Layer 2 Technology

This paper describes some of the interesting technical issues that arose in the design of TRILL (TRansparent Interconnection of Lots of Links), a technology being standardized in IETF, that combines the ease of configuration usually associated with layer 2, with the flexibility, robustness, and route optimizations usually associated with layer 3. In addition to describing the issues, we describe the alternative proposals, and the rationale behind the resolutions.