Davide Cherubini - PhD Thesis - UniCA Eprints

6.4 LP modelsP(h) - Set of edges which belong to path hP(f) - Set of paths for commodity fd fx f ij- Effective bit rate of flow f- Share of flow f carried by ISIS and traversing link (i, j)Variablesu maxis fp hmaximum utilization in the network - to be minimizedShare of flow f carried by ISISShare of flow f which uses path h with MPLS technologyModel for GRPz = min(u max ) (6.51)∑is f · x f ij +∑p h ≤ u max · c ij ∀(i, j) ∈ A (6.52)f∈F∑h∈P(f)h:(i,j)∈P(h)p h = d f − is f ∀f ∈ F (6.53)p h ≥ 0 ∀h ∈ P(f) (6.54)is f ∈ [0, d f ] ∀f ∈ F (6.55)Survivability ConstraintsIn this case, the survivability constraints are the sum of two distinct terms.The first term is the part of traffic traversing the link (i, j) when the edge l fails.This flow is composed by the former IS-IS traffic and the MPLS traffic affectedby the failure rerouted by IS-IS.The second term is the MPLS flow unaffected by the failure of the edge l.61