Conflict detection and resolution in two-dimensional prefix router tables

  • Authors:
  • Haibin Lu;Sartaj Sahni

  • Affiliations:
  • Department of Computer Science, University of Missouri-Columbia, Columbia, MO;Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL

  • Venue:
  • IEEE/ACM Transactions on Networking (TON)
  • Year:
  • 2005

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Abstract

We show that determining the minimum number of resolve filters that need to be added to a set of two-dimensional (2-D) prefix filters so that the filter set can implement a given policy using the first-matching-rule-in-table tie breaker is NP-hard. Additionally, we develop a fast O(nlogn + s) time, n where is the number of filters and s is the number of conflicts, plane-sweep algorithm to detect and report all pairs of conflicting 2-D prefix filters. The space complexity of our algorithm is O(n). On our test set of 15 2-D filter sets, our algorithm runs between 4 and 17 times as fast as the 2-D trie algorithm of A. Hari et al. (2000) and uses between 1/4th and 1/8th the memory used by the algorithm of Hari et al. On the same test set, our algorithm is between 4 and 27 times as fast as the bit-vector algorithm of Baboescu and Varghese (2002) and uses between 1/205 and 1/6 as much memory. We introduce the notion of an essential resolve filter and develop an efficient algorithm to determine the essential resolve filters of a prefix filter set.