deploying and managing ip over wdm networks - Index of

56 Deploying and Managing IP over WDM Networks
modification of intelligent network elements (OSMINE) [1] or the multitechnology
network management (MTNM) [2] between the NML and the EML.
This chapter is intended to present the WDM resources to be managed,
both at network-device level and at network level, as well as the technologies
used for the most common management procedures. To fulfill this objective, we
have the following structure: Section 4.2 summarizes the main network devices
encountered in WDM networks already mentioned in Chapter 2 when describing
the architecture of the OTN, while Section 4.3 presents the layered model of
the OTN. Devices and entities exposed in these two sections will be the subject
of management. Section 4.4 enters in detail with the management issues following
a functional organization in three management areas: configuration, fault,
and performance management. This sections ends with a reference to the main
standards or de facto standards used in management interfaces.
4.2 The WDM Network Elements
The two most important network elements within WDM networks are the
OADM and the OXC. Similarly to the SDH ADM, the OADM allows the
grooming or splitting of the optical signal along the transmission path, permitting
the construction of more complicated and flexible networks topologies.
Consequently, a WDM ring can be constructed in a way similar to SDH rings.
The OXC network element allows the (de)multiplexing of two or more
optical signals into the transmission fiber or vice versa. Optical multiplexers/demultiplexers,
optical switches, and wavelength converters usually compose
the OXCs. Figure 4.1 depicts the architecture of an OXC element. The incoming
optical signal is demultiplexed into several wavelengths that are sent to the
optical switches. The optical switches route the wavelengths to optical multiplexers,
creating one optical signal suitable for transmission. Wavelength converters
can be used between the optical switches and the multiplexers, providing
more routing flexibility.
4.3 Optical Transport Network Modeling
Introduced in Chapter 2, OTNs provide transport services via lightpaths and
can be considered the next step in the evolution from WDM point-to-point networks.
A lightpath is simply a high-bandwidth pipe carrying data up to several
gigabits per second. An OTN is composed of several OXCs, which are connected
in a certain topology of choice. Lightpaths are set up and torn down
either by the management system of the network or by means of signaling. The