Internet vulnerability studies typically consider highly central nodes as favorable targets of intelligent (malicious) attacks. Heuristics that use redundancy adding k extra links in the topology are a common class of countermeasures seeking to enhance Internet robustness. To identify the nodes to be linked most previous works propose very simple centrality criteria that lack a clear rationale and only occasionally address Intra-domain topologies. More importantly, the implementation cost induced by adding lengthy links between nodes of remote network locations is rarely taken into account. In this paper, we explore cost-effective link additions in the locality of the targets having the k extra links added only between their first neighbors. We introduce an innovative link utility metric that identifies which pair of a target's neighbors aggregates the most shortest paths coming from the rest of the nodes and therefore could enhance the network connectivity, if linked. This metric drives the proposed heuristic that solves the problem of assigning the link budget k to the neighbors of the targets. By employing a rich Intra-domain networks dataset we first conduct a proof-of-concept study to validate the effectiveness of the metric. Then we compare our approach with the so-far most effective heuristic that does not bound the length of the added links. Our results suggest that the proposed enhancement can closely approximate the connectivity levels the so-far winner yields, yet with up to eight times lower implementation cost.
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