A well-known approach to intradomain traffic engineering consists in finding the set of link weights that minimizes a network-wide objective function for a given intradomain traffic matrix. This approach is inadequate because it ignores a potential impact on interdomain routing. Indeed, the resulting set of link weights may trigger BGP to change the BGP next hop for some destination prefixes, to enforce hot-potato routing policies. In turn, this results in changes in the intradomain traffic matrix that have not been anticipated by the link weights optimizer, possibly leading to degraded network performance. We propose a BGP-aware link weights optimization method that takes these effects into account, and even turns them into an advantage. This method uses the interdomain traffic matrix and other available BGP data, to extend the intradomain topology with external virtual nodes and links, on which all the well-tuned heuristics of a classical link weights optimizer can be applied. A key innovative asset of our method is its ability to also optimize the traffic on the interdomain peering links. We show, using an operational network as a case study, that our approach does so efficiently at almost no extra computational cost.
Cerav- have already shown in @cite_14 that the link weights found by a LWO may change the intradomain TM considered as input. In that paper they also show that applying LWO recursively on the resulting intradomain TM may not converge. They propose a method that keeps track of the series of resulting TMs and at each iteration they optimize the weights for the previous resulting intradomain TMs simultaneously. However, they do not consider the general problem with multiple exit points for each destination prefix, let alone taking advantage of it.
@cite_14
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Link weight optimization is shown to be a key issue in engineering of IGPs using shortest path first routing. The IGP weight optimization problem seeks a weight array resulting an optimal load distribution in the network based on the topology information and a traffic demand matrix. Several solution methods for various kinds of this problem have been proposed in the literature. However, the interaction of IGP with BGP is generally neglected in these studies. In reality, the optimized weights may not perform as well as expected, since updated link weights can cause shifts in the traffic demand matrix by hot-potato routing in the decision process of BGP. Hot-potato routing occurs when BGP decides the egress router for a destination prefix according to the IGP lengths. This paper mainly investigates the possible degradation of an IGP weight optimization tool due to hot-potato routing under a worst-case example and some experiments which are carried out by using an open source traffic engineering toolbox. Furthermore, it proposes an approach based on robust optimization to overcome the negative effect of hot-potato routing and analyzes its performance