tals and Present Architectures TABLE 3.8 Qualitative Comparison among Different IP Convergent Network Architectures Physical Physical Layer Layer 2 Layered Layer Global Over- Architecture Topology Protection Restoration Protection Restoration Provisioning (%) Rings Shared Next Gen SONET Next Gen SONET Rings Shared MPLS over DWDM MPLS over DWDM 1+1 (link based) MPLS over DWDM MPLS over OTN MPLS over OTN Rings Shared physical layer dedicated protection has higher availability with respect to mesh network built with the MPLS over DWDM technology where only MPLS restoration is implemented. Also this aspect will be analyzed in a quantitative way in Chapter 8. From the table, the effect of multilayer survivability emerges, for example, comparing line one with line six. In both cases, protection and restoration are both present, but in the first case they are at the same layer, in the second on different layers. The effect is that, while in the POS case the network manager of the physical layer can coordinate the two strategies, for example, avoiding 1+1 protection for restoration dedicated paths, in the second case this is not possible since restoration is on the MPLS layer while protection is on the physical one. Due to this, when the capacity allocation proposals pass from the MPLS layer to the OTN layer, OTN cannot distinguish restoration paths from working paths and provides dedicated protection for both. This is a side effect of the absence of a common control plane and is also an important cause of inefficiency of the network. 3.4.2 Network Dimensioning and Cost Estimation After a performance qualitative comparison, we will carry out in this section a more quan- titative comparison based on network cost as defined at the beginning of Section 3.4. Since we are dealing with multilayer networks, a synthesis algorithm for these networks is needed. In general, carriers have their own dimensioning algorithms that are often technol- ogy specific; network optimization means decreasing CAPEX and OPEX, SO it has a great im