Optical Network Control: Architecture, Protocols, and Standards

11.3. Routing with Simple Constraints

The shortest path algorithms described above allow us to select an optimal path based on a set of chosen link weights. We can combine the shortest path technique with a simple graph pruning approach to include certain classes of constraints. In general, this approach is applicable when specific nodes or links can be excluded from the path based on their attributes. This is illustrated in the following examples.

11.3.1. Link Protection Constraints Example

Consider the network shown in Figure 11-2, where each link is assigned a cost and unprotected links are indicated by dashed lines. The shortest path from NE 1 to NE 7, regardless of individual link protection capabilities, is (NE 1, NE 3, NE 6, NE 7), as ...