Naturally the two processes have to be coordinated in order to avoid those problems that can occur in a bad designed multilayer restore mechanism. The most important phenom- enon to be avoided is protection instability: if a path is protected at layer 1 and then also restored at layer 2, restoration can cause switching off optical power on the layer 1 protec- tion path. Layer 1 protection mechanism could interpret the fact as a new failure and try to protect the considered and other paths against it, with service disruption and the pos- sibility to start an oscillatory phenomenon between the two layers. The simpler way to coordinate two reliability mechanism located at different layers is to introduce a sufficiently long hold-off time at the upper layer SO to give to the lower layer sufficient time to stabilize. More sophisticated methods however exists to avoid the increment of recovery time due to the fact that the hold-off time is the same for any failure event. These methods are based on the use of signaling protocols to advertise all the rel- evant network entities of the started protection switch. It is also interesting to compare, at last in a qualitative way, multilayer reliability with a multistrategy single layer reliability, where, for example, both dedicated protection and wavelength level restoration are carried out by OXCs directly at the optical layer. The basic multilayer approach advantage is that, in case the optical reliability mecha- nism does not work or is compromised by a multiple failure, the successive step is to route MPLS LSPs individually, exploiting the small granularity to perform more efficient restoration. This is a principle similar to that of grooming, where complexity at layer 2 is traded with more effective exploitation of transmission capacity at layer 1. We will analyze multilayer survivability with the same method used in the previous section: we will design first the network for the required traffic, SO deriving information on the network cost. Telecommunication Networks TA