dwidth Usage Dedicated protection uses exactly the same bandwidth for protection that for working GLSPs. Shared protection is a bit more efficient. In 1:1 protection, the spare bandwidth is used for low-priority traffic, generally best effort services. In this way also the protection bandwidth is used during the normal network working. Restoration with presignaled GLSPs and reserved bandwidth is generally slight better than shared protection. On the contrary, restoration with complete reprovisioning exploits the bandwidth at best. 8.5.2.2 Recovery Time All protection mechanisms, due to the preprovision of the protection path, are very fast. The SDH/SONET standard of 50 ms between the failure and the complete service resto- ration is the reference for these methods. Restoration with presignaling and bandwidth reservation has a speed similar to protection, while the other two forms of restoration in general are quite slow. 8.5.2.3 Specific Protocols Optical path 1 + 1 protection requires no real-time protocol, even if obviously the pro- tection setup has to be advertised at the network elements and at the network manager. However, these communications does not condition the speed of the protection mecha- nism that is completely hardware. In case of shared protection, a dedicated specific protocol has to be realized in order to manage the protection resources sharing and coordinate the protection switch on and switch off. The SDH/SONET automatic protection switching protocol (APS) is an example of such a protection dedicated protocol. Restoration processes are completely managed by the control plane and uses control plane standard protocols. 8.5.2.4 QoS Issues In the cases of shared protection and, mainly, of restoration with complete reprovisioning of the path, it is difficult to guarantee some elements of the QoS, i.e., the network traversing time. If services with a high-level QoS are concerned, other survivability methods should be used. 8.5.2.5 Quantitative Comparison To perform a quantitative comparison, for e