Information Technology Reference
In-Depth Information
Chapter 5
D
ESIGN OF
M
ETRO
H
UBS FOR
O
PTICAL
M
ETRO
N
ETWORKS
Yiu-Wing Leung
1
Department of Computer Science, Hong Kong Baptist University,
Kowloon Tong, Hong Kong
A
BSTRACT
Nowadays many local networks provide high-speed access to end users (e.g., Gigabit
Ethernet and optical access networks). Accordingly, each metro network should have a
large bandwidth in order to transport the traffic between the local networks and the wide
area backbone network. To fulfill this requirement, an
optical metro network
uses optical
fibers to connect the local networks to the backbone network via a
metro hub
. In this
chapter, we describe our recent design of metro hubs called
multi-passive-combiner hubs
[1-2]. A multi-passive-combiner hub is composed of passive combiners and
demultiplexers. Within the hub, wavelength channels are assigned to the input-output
pairs to fulfill the traffic requirements while avoiding wavelength conflict. The multi-
passive-combiner hub has three major advantages: i) it has low cost and high reliability
because it only uses passive optical components, ii) it can efficiently transport non-
uniform metro traffic via non-uniform channel assignment within the hub, and iii) it can
easily be scaled up to provide more channels for the ever-increasing traffic load.
1.
I
NTRODUCTION
The Internet can be viewed as a three-level hierarchy: local networks, metro networks
and backbone networks [3]. Nowadays many local networks provide high-speed access to end
users (such as Gigabit Ethernet and optical access networks [4-5]), and a backbone network
can provide very large bandwidth by using optical fibers [6-12]. Accordingly, a metro
network should have a large bandwidth to transport the traffic among many local networks
