Optimizing IGP link weights for energy-efficiency in multi-period traffic matrices

Abstract

International audienceRecently, due to the increasing power consumption and worldwide gases emissions in ICT (Information and Communication Technology), energy efficient ways to design and operate backbone networks are becoming a new concern for network operators. Since these networks are usually overprovisioned and since traffic load has a small influence on power consumption of network equipments, the most common approach to save energy is to put unused line cards that drive links between neighboring routers into sleep mode. To guarantee QoS, all traffic demands should be routed without violating capacity constraints and the network should keep its connectivity. From the perspective of traffic engineering, we argue that stability in routing configuration also plays an important role in QoS. In details, frequent changes in network configuration (link weights, slept and activated links) to adapt with traffic fluctuation in daily time cause network oscillations. In this work, we propose a novel optimization method to adjust the link weights of Open Shortest Path First (OSPF) protocol while limiting the changes in network configurations when multi-period traffic matrices are considered. We formally define the problem and model it as Mixed Integer Linear Program (MILP). We then propose an efficient heuristic algorithm that is suitable for large networks. Simulation results with real traffic traces on three different networks show that our approach achieves high energy saving while keeping the networks in stable state (less changes in network configuration)

Energy management in communication networks: a journey through modeling and optimization glasses

“…x [72] x x [73,74] x x [75,76] x x [77] x Multi-topology routing [78,79] x Energy-Levels [80][81][82][83] x Node expansion, Multiple sleeping states [48,84] x x [85] x x x [86] x x [87,88] x x x x x [89] x [90] x x x x [91] x x Bi-objective function for energy and delay [92] x x x x hop-by-hop routing [93,94] x x x x Two macro-periods [95] x x [96] [97] x [55,98,99] x Redundancy elimination [100,101] x x x x [102] x x x Approximated shared and dedicated protection [103] x x x x [104] x x Failure probabilities x New power state [110] x x [111] x ECMP and robustness [53] Fully splittable [112] free splitting ratio [113,114] [ 115,116] x x Traffic unaware because only link loads considered [117,118] x x OSPF is modified [119] x OSPF is mo...…”

“…Some of the most popular studies on EANM, [22,[63][64][65], explicitly address the variant of the IP-BEANM problem (1-8) adapted to model sleeping capabilities (see Section 3.4). We recall that (i) routing is flow based [20,105,106] x x x [107] x x x [108] x x x [109] x x x [110] x x x [111] x x x [53] x x x x [112] x x x x [113,114] x x x x [115,116] x x x [117,118] x x x x [119] x x x x [120] x x x and fully splittable, that is, flow variables f d i j are real and nonnegative, (ii) the objective function minimizes the fixed energy cost paid to keep a node (router) or a link (network interface) in the active state and no proportional consumption component is considered, i.e., objective function (1) is replaced by (20), (iii) link capacity constraints (5) are adjusted as in (21), (iv) each link is assumed to be made by a single network interface or line card, i.e.,…”

“…A multi-period scenario similar to that addressed in [57] but based on shortest path routing is addressed in [111].…”

Robust energy-aware routing with redundancy elimination

“…Therefore during normal periods, the traffic load is typically well below the network capacity. Following this observation, people have proposed energy-aware routing (EAR) to minimize the number of used links while all the traffic demands are routed without any overloaded links [16,27,40,24,33].…”

Energy saving in carrier-grade networks: A survey

“…Figure 18. General overview of ETE [93] Interesting works have dealt with the multi-period traffic optimisation; among others: [163][164][165]190]. Two MILPbased algorithms are presented in [163], the first adopts a fixed configuration for routing along multi periods of daily time, while the second MILP allowing flexibility of routing path to the network administrator.…”