deploying and managing ip over wdm networks - Index of

244 Deploying and Managing IP over WDM Networks
IP subnetwork
Optical
subnetwork
NNI
End-to-end IP connectivity
NNI or UNI NNI or UNI
Optical
subnetwork
Figure 13.1 Integrated IP/WDM reference network.
routers. Physical topology of the optical layer consists of multiple optical subnetworks
interconnected by optical links. Hence, the model represents a network
evolved from the interconnection of different multivendor administrative
domains for the provision of automatically switched end-to-end services. While
interworking of the subnetworks is done by means of a standardized NNI interface,
interaction between the IP routers and the optical layer is carried out either
by UNI-like interface under the overlay interconnection model or by NNI
under the peer and augmented models. The optical layer is responsible for the
provision of point-to-point connectivity between the routers by means of fixedbandwidth
optical paths. Thus, the network virtual topology is formed by a set
of lightpaths connecting source-destination pairs of IP routers. Although static
at the moment, this topology is expected to become automatically reconfigurable
in the near future, allowing dynamic lightpath setup as well as automatic
lightpath restoration. Implementation of control protocols between the IP and
the optical layers, as well as between the optical subnetworks, and their interworking
with NMSs can follow different interconnection models, each representing
multiple integration challenges. The most important ones are covered in
the remaining sections of this chapter.
13.2 The Outlook from the IST-OPTIMIST Project
Optical
subnetwork
On May 1, 2000, the IST thematic network project OPTIMIST was launched.
This project aims to highlight the research and development effort spent in the
NNI
IP subnetwork