Routing, Wavelength Assignment in Optical
Networks Using an Eﬃcient and Fair EDP
Algorithm
Pallavi Manohar and V. Sridhar
?
Applied Research Group, Satyam Computer Services Ltd.,
14 Langford Avenue, Lalbagh Road, Bangalore 560 025 INDIA.
{
pallavi
mm, sridhar
}
@satyam.com
Abstract.
Routing and
wavelength assignment (RWA) problem in
wavelength routed optical networks is typically solved using a combi-
nation of integer programming and graph coloring. Such techniques are
complex and make extensive use of heuristics. RWA with maximum edge
disjoint path (EDP) using simple bounded greedy algorithm is shown
to be as good as previously known solution method. In this paper, we
present shortest path Frst greedy algorithm for maximum EDP with
construction of path conﬂict graph which gives fair and eﬃcient solution
to the RWA problem in optical networks.
Keywords:
Optical Networks, Routing and Wavelength Assignment,
Edge Disjoint Path Algorithms.
1
Introduction
Routing and wavelength assignment (RWA) for the lightpaths of the virtual
topology in wavelength routed optical networks is typically solved in two parts –
lightpath routing, to determine the route of the lightpaths on the physical topol-
ogy, and wavelength assignment, to assign the wavelengths to each lightpath in
the virtual topology such that wavelength constraints are satisFed for each phys-
ical link. The RWA problem for a given physical network and virtual topology
is known to be NP-complete. ±urther, routing and wavelength assignment prob-
lems are each known to be NP-complete [3] and many heuristic solutions have
been proposed [7,8]. See [3,10,11] for a survey of the various solutions to the
RWA problem. Lightpath routing is done by Frst selecting the lightpaths and
then assigning routes to them. The order in which the lightpaths are assigned
can be selected by di²erent heuristic schemes such as random, Fxed, longest-
Frst, or shortest-Frst. Routes can be found by techniques such as shortest path
algorithm, weighted shortest path, or
K
−
shortest path algorithms. The route is
selected from the available candidates using di²erent schemes such as random,
Frst-Ft, or probability. The RWA problem is also solved by formulating it as an
?
Member, IEEE
M. Bubak et al. (Eds.): ICCS 2004, LNCS 3038, pp. 1178–1184, 2004.
c
±
Springer-Verlag Berlin Heidelberg 2004