Definition 3.1 (Multi-constrained QoS routing problem). Given an
undirected graph G(V, E) with each edge e is associated with k
weight functions where ωl(e) > 0, ∀ e ∈ E and 1 ≤ l ≤ k. A constants
vector c = (c1, c2, . . ., ck). A multi-constrained QoS routing problem
consists in finding a path p between a source s and destination d,
so that, ωl(p) ≤ cl, where 1 ≤ l ≤ k.