In this work we consider the problem of routing bandwidth-guaranteed flows with time-variable bandwidth profiles on a MPLS network. We assume that each demand is routed in an explicitly routed LSP, and the amount of bandwidth that must be reserved along the LSP varies during the day according to a piece-wise mask, which is known in advance. The time-of-day bandwidth profiles can be explicitly declared by the VPN customers in the SLA, or alternatively predicted by the ISP based on past measurements.In this framework, we propose a simple on-line algorithm for optimal selection of LSP paths. We also provide an ILP formulation for the associated off-line problem, and adopt it as a reference performance bound for the on-line algorithm.Additionally, we compare the performances of fixed and variable routing in presence of time-variable bandwidth profiles. The results presented here suggest that the a priori knowledge of the per-demand traffic profiles can be exploited to achieve a fixed routing configuration, which can be marginally improved by variable reconfigurations. We relate our findings with a couple of previous works that in different application contexts achieved similar results.
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