k-Pairwise Cluster Fault Tolerant Routing in Hypercubes

  • Authors:
  • Qian-Ping Gu;Shietung Peng

  • Affiliations:
  • -;-

  • Venue:
  • IEEE Transactions on Computers
  • Year:
  • 1997

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Abstract

In this paper, we introduce a general fault tolerant routing problem, cluster fault tolerant routing, which is a natural extension of the well studied node fault tolerant routing problem. A cluster is a connected subgraph of a graph G, and a cluster is faulty if all nodes in it are faulty. In cluster fault tolerant routing (abbreviated as CFT routing), we are interested in the number of faulty clusters and the size of the clusters that an interconnection network can tolerate for certain routing problems. As a case study, we investigate the following k-pairwise CFT routing in n-dimensional hypercubes Hn: Given a set of faulty clusters and k distinct nonfaulty node pairs (s1, t1), ..., (sk, tk) in Hn, find k fault-free node-disjoint paths si驴ti, 1 驴i驴k. We show that Hn can tolerate n驴 2 faulty clusters of diameter one, plus one faulty node for the k-pairwise CFT routing with k = 1. For n驴 4 and $2 \le k \le \lceil n/2 \rceil,$ we prove that Hn can tolerate n驴 2k + 1 faulty clusters of diameter one for the k-pairwise CFT routing. We also give an O(kn log n) time algorithm which finds the k paths for the mentioned problem. Our algorithm implies an O(n2 log n) time algorithm for the k-pairwise node-disjoint paths problem in Hn, which improves the previous result of O(n3 log n).