ry link there is an incomplete DWDM system with available wavelengths, route the GLSP and go to END. If there is no wavelength with sufficiently capacity available on one or more links, eliminate those links from the topology. Find the shortest path in the new topology. If on every link there is an incomplete DWDM system with available wavelengths, route the GLSP and go to END. Return to the original topology and to the original shortest path. Add a new DWDM system when needed and route the GLSP. Naturally this is only one of the possible flavors that OSPF like algorithms can have when used in network design tools. For example, we have listed a version that opens a new DWDM if the second shortest path is also unavailable, but this is not needed. It would be possible to look for the third shortest path and SO on. Finally, in this paragraph we have considered explicitly the cost of the links, but the cost of the nodes can be added using the same criterion. Convergent Network Management and Control Plane 8.4.3.2 Constrained Routing A different type of routing can be applied when designing a network, more oriented to limit the overall network cost. This is the cost constrained routing whose algorithm can be described as follows: Set an order for the GLSP setup requests. For each GLSP, find all the paths connecting source and destination. With an opportune cost model compute the incremental cost related the possibil- ity of routing the new GLSP on every possible route. Among the considered paths chose that with the minimum incremental cost. Several routing algorithms can be devised introducing different kind of constrains, for example, on the QoS, on the capacity and SO on. A class of interesting constrains are the SO called dynamic once. A routing constraint is called dynamic when the tags that are put on the links and drive the constrained routing are not constant but change while the situation of the network evolves. Naturally also in this case an order in which the setup of the GLSP is request has to be fixed. A c