The chord version for SONET ADMs minimization

Leah Epstein, Asaf Levin

Research output: Contribution to journalArticlepeer-review


We consider a problem which arises in optical routing. WDM/SONET rings are a network architecture used by telecommunications carriers for traffic streams. The dominant cost factor in such networks is the total number of add-drop multiplexers (ADMs) used. A list of traffic streams to be routed between pairs of nodes is given. In this paper we consider the problem where we need to assign a route and a wavelength to each traffic stream, minimizing the total number of used SONET ADMs. This is called the chord version of the SONET ADMs minimization problem, to denote the fact that the routing is not given a priori. The best previously known approximation algorithms for this problem have the performance guarantee of 32. We present an improved algorithm with performance guarantee of exactly 107≈1.42857. Moreover, we study some natural heuristics for this problem, and give tight analysis of their approximation ratios.

Original languageEnglish
Pages (from-to)337-346
Number of pages10
JournalTheoretical Computer Science
Issue number3
StatePublished - 16 Dec 2005

Bibliographical note

Funding Information:
∗Corresponding author. E-mail addresses: (L. Epstein), (A. Levin). 1Research supported by Israel Science Foundation (Grant no. 250/01).


  • Approximation algorithms
  • Optical networks

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science (all)


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