Reliability assessment of interconnection networks is critical to the design and maintenance of multiprocessor systems. The (n, k)-enhanced hypercube Q_{n,k} as a variation of the hypercube Q_{n}, was proposed by Tzeng and Wei in 1991. As an extension of traditional edge-connectivity, h-extra edge-connectivity of a connected graph G, \lambda_h(G), is an essential parameter for evaluating the reliability of interconnection networks. This article intends to study the h-extra edge-connectivity of the (n,2)-enhanced hypercube Q_{n,2}. Suppose that the link malfunction of an interconnection network Q_{n,2} does not isolate any subnetwork with no more than h-1 processors, the minimum number of these possible faulty links concentrate on a constant 2^{n-1} for each integer \lceil\frac{11\times2^{n-1}}{48}\rceil \leq h \leq 2^{n-1} and n\geq 9. That is, for about 77.083 percent values of h\leq2^{n-1}, the corresponding h-extra edge-connectivity of Q_{n,2}, \lambda_h(Q_{n,2}), presents a concentration phenomenon. Moreover, the above lower and upper bounds of h are both tight.

翻译：互连网络的可靠性评估对多处理器系统的设计与维护至关重要。作为超立方体Q_n的变体，(n,k)-增强超立方体Q_{n,k}由Tzeng和Wei于1991年提出。作为传统边连通性的推广，连通图G的h-额外边连通度λ_h(G)是评估互连网络可靠性的重要参数。本文旨在研究(n,2)-增强超立方体Q_{n,2}的h-额外边连通性。假设互连网络Q_{n,2}的链路故障不会隔离任何不超过h-1个处理器的子网络，则对于每个满足\lceil\frac{11\times2^{n-1}}{48}\rceil \leq h \leq 2^{n-1}且n\geq 9的整数h，这些可能故障链路的最小数量集中于常数2^{n-1}。也就是说，对于约77.083%的满足h\leq2^{n-1}的取值，Q_{n,2}对应的h-额外边连通度λ_h(Q_{n,2})呈现出集中现象。此外，上述h的下界和上界均为紧界。