Photonic Network Communications, 5:3, 247±257, 2003
# 2003 Kluwer Academic Publishers.Manufactured in The Netherlands.
A Fiber Routing Problem in Designing Optical Transport Networks
with Wavelength Division Multiplexed Systems
Department of Industrial Systems and Information Engineering, Korea University, Sung-Buk Ku Anam Dong 5-1, Seoul 136-701, Korea
LG Electronics, Dongan-Ku Hogye-Dong 533, 431-080, Anyang, Kyongki-Do, Korea
Electronics and Telecommunications Research Institute, Yusong-Gu Kajong-Dong 161, Taejon, Korea, 305-350
Received April 28, 2002; Revised and Accepted October 9, 2002
Abstract. In this paper, we consider a ®ber routing problem arising from the design of optical transport networks.The problem is to ®nd an
optimal routing of multiple rings and an optimal location of wavelength division multiplexed (WDM) systems for carrying demand traf®c.This
problem can be conceptualized as a Steiner (multiple) ring problem with link capacity constraints.We formulate the problem as a mixed-integer
programming model and develop a new branch-and-cut procedure along with preprocessing routines and valid inequalities for optimally solving
the problem.Exploiting the inherent special structures of the formulation, we focus on developing strong valid inequalities and devising an
effective Tabu search heuristic for solving large-scale problems.Computational results indicate that preprocessing rules and valid inequalities
provide a tight lower bound, and in turn reduce the effort required to solve the problem within the framework of the branch-and-cut procedure.
Moreover, the proposed Tabu search heuristic works quite well for solving large-scale problems.Motivated by promising computational results,
we provide insights into implementing the proposed branch-and-cut procedure for deploying ®ber optic networks in practice.
Keywords: telecommunication networks, wavelength division multiplexed (WDM) systems, synchronous optical network (SONET), branch-
and-cut, tabu search, capacitated Steiner ring problem
In this paper, we consider a ®ber routing problem
arising from the deployment of synchronous optical
networks (SONET) and wavelength division multi-
plexed (WDM) systems.The SONET is the most
widely used transmission technology over optical
networks, and the WDM is an emerging technology
for increasing the transmission capacity of optical
®bers.The typical capacity of current SONET carries
2.4 Gbps on a single channel ®ber, which is equivalent
to 38 000 voice circuits.Thus, a failure in a single link
may result in a tremendous loss in customer service.
In response, telecommunication companies are
adopting SONET self-healing ring (SHR) architec-
tures that guarantee link survivability of the network
(see the technical details of SONET SHR, Wu, 1992).
At the same time, network operators, spurred by
persistent projections of vastly increased demands for
bandwidth of the Internet, have been driven by a
vision of an optical network that could evolve to meet
future demands for increased capacity.From a
transport networking perspective, the essential ele-
ments are an ef®cient and cost-effective capacity
expansion and survivability mechanisms to support
improved reliability of data networks.It was
recognized that the ef®cient implementation of
capacity expansion and routing could dramatically
reduce overall network cost (see the techno-economic
issue of optical transport networks in Bonenfant .
Let us ®rst describe the modeling of capacity
expansion of optical networks.As depicted in Fig.
1(a), the transmission of traf®c between the nodes on a
link requires a special type of equipment at each node
that is capable of adding and dropping the traf®c.This
device is called a SONET add-drop multiplexer