 traffic from the backup path back to the working path The restoration recovery time TRR depends on the type of restoration is used (compare Section 8.4.2.2). In particular we have Type 1: TRR = TDET + Type 2: TRR = TDET + THOP + TNOT + TBRA + TBS -TBA + Tsw + TCR (8.41) Type 3 TRR = TDET + THOP + TNOT + -TBRA + TBSA + TBA Tsw + TCR On the contrary, the protection recovery time TPR does not include the backup routing and backup signaling since the backup path was preestablished: = TDET +THOF+TNOT+TBA+Ts + TCR (8.42) Convergent Network Management and Control Plane When a failure occurs, connections are lost until the traffic is switched over to the backup path. The amount of lost information due to a connection loss is a function of TPR or TRR and the number of LSRs directly corrupted by the failure. Generally, losses cannot be totally avoided by most of the protection mechanisms exceptions being 1 + 1 protection. In the case of protection techniques, the time required to start the switchover is expressed (8.43) In case of restoration the switchover can be avoided: after restoration the new routes becomes working routes and when the failed capacity is restored it is included among the back-up resources. 8.5.2 Protection versus Restoration In this section, we will consider the case of a single layer (the optical layer). One surviv- ability mechanism is implemented in the network, either a type of protection or a type of restoration. Since link-dedicated protection is quite trivial within a GMPLS context, we will consider the following forms of optical path protection: End-to-end 1 + 1 Dedicated Protection End-to-end 1 + 1 Shared Protection End-to-end 1:1 Shared Protection As far as restoration is concerned, as we have already anticipated in the previous section, three methods of restoration are considered: 1. End-to-end GLSP restoration with complete re-provisioning (type 1 restoration): A recovery path is not established before a failure. After the fault notification, the ingress layer 2 node starts the procedure 