A greenfield optical network is defined as a brand-new optical network; everything starts from scratch. Fibers and hardware switch facilities need to be deployed.

For this type of dimensioning problem, given parameters generally include:

(1) A physical network topology, which can be the lowest duct layer. All the traffic demands in the client layer have to follow one of physical routes in the duct layer. This physical topology information also provides information on potential link cost to establish a direct virtual link between a pair of locations (i.e., nodes) on the server layer. The cost can be determined based on the proportional relationship to the physical distance between the two locations. Of course, it is also possible that the physical topology is not a given parameter. In this case, a physical topology design should be carried out to explore an optimal topology, based on a forecasted traffic demand matrix and given costs, to establish physical links between node pairs.

(2) A set of traffic demand matrices in the client layers. All the traffic demands in each client layer follow a common capacity granularity, e.g., OC-1. The distribution of traffic demands can be in various formats ranging from a uniform, random, to hub-based distribution.

(3) The traffic demands between each node pair are routed in either an integrated fashion or a splitting fashion. The former means that each demand must travel the same route, while the latter implies that the demand is allowed to take different routes to reach the destination.

The objective is to dimension a network with a minimum network cost or maximum network throughput. Output data include (1) a set of connections in each network layer, (2) a list of switch facilities, (3) overall performance analyses, and (4) a total of network cost.

Specifically, in each layer a virtual topology would be formed to server upper client layer traffic demands. Each virtual link on a virtual topology is associated with a pair of add/drop ports in the corresponding network layer, thereby allowing us to compute the detailed list of hardware facilities such as the number of add/drop ports and switch module scale in each network layer. As a result, a total network dimensioning cost can be computed.

See next section: Network dimensioning procedure.