This presentation was by Rick Boivie (IBM). Route loops are created because not all nodes learn about topology changes at the same time, then the algorithm was presented on how to do loop preventionand was based around the concept of a route vortex
Question from Zheng Wang why this functionality not o be present at the IP level.The answer was that this is done in order to deal with all overlaying protocols IPX, AppleTalk, IP etc. independent of routing protocols.
Then the issue of preventing loops with metrics and Joel Halpern said that the algorithm is a label routing protocol.