Thursday, June 3, 16h00, IMB 2A crucial issue for network design is the capability of a network to restore traffic when some components fail. Since restoring may be expensive or cause transmissions delays, a key property is requiring that traffic not affected by a failure is not re-routed in failure situations. We investigate how to implement this property in networks, such as Ethernet networks, where traffic is commonly routed on the edges of a shortest path tree, obeying protocols of the Spanning Tree Protocol family.This is joint work with F Grandoni, G. Nicosia, L. Sanità.