**2.1 Acquiring information about the network and link cost calculation**

The parameters of the link-cost metric should directly represent the fundamental network characteristics and the changing dynamics of the network status. Furthermore, they should be orthogonal to each other, in order to eliminate unnecessary redundant information and inter-dependence among the variables (Wang & Crowcroft, 1996). Depending on the composition rule we distinguish additive, multiplicative, concave and convex link-cost metrics (Wang, 1999). In additive link-cost metrics the total cost of the path is a sum of costs on every hop. Additive link costs include delay, jitter, cost and hop-count. Total cost of the path in the case of multiplicative link-cost metrics is a product of individual costs of links. A typical example of multiplicative link cost is link reliability. In concave and convex link-cost metrics the total cost of the path equals the cost on the hop with the minimum and maximum link cost respectively, and a typical example of link-cost metric is the available bandwidth.
