When we consider DWDM and installation of new fiber for capacity increase as two possible alternatives, the DWDM is much more favorable to installing new fiber cable. Particularly in distances less than 400 miles where no DWDM regenerators are required, the
DWDM provides much higher cost reduction than the new fiber installation. This is mainly because the rate of capacity increase is much higher relative to rate of DWDM equipment cost.
In the case of fiber installation, it is very difficult to achieve cost reduction due to the very labor intensive nature of the process. As it can be seen in Figure 1-3, the cost of fiber installation linearly increases with distance. Hence, it is obvious to assume that significant
bandwidth cost reduction will mainly come from the utilization of DWDM technology.
Figure 1-4 illustrates implementation of the DWDM-based transport system for 500 km and 1000 km distances. Based on the current technology, it is necessary to regenerate each wavelength at every 500 km distance due to the accumulative noise effect from the
optical line amplifiers. It is expected that further advances in optical technology will push the maximum distance without signal regeneration to longer distances, hence reducing the cost of DWDM further for the long-haul transport segment.
D. Market Opportunities
The two emerging technologies DWDM- and ATM-based VP Virtual Path present very significant opportunities in the transport market today. These two technologies are capable of collapsing the present SONET multiplexing hierarchy to achieve a more efficient
and cost effective transport medium.
For example, it is possible to use both the DWDM and ATM technologies to collapse the current SONET hierarchy into a leaner, more efficient and cost effective transport system. In the long-term, advances in optical transmission and optical switching will play a pivotal
role in terms of increasing the wavelength density and making it possible to implement a fully optical communication network.
Figure 1-4 DWDM implementation a for 500 km distance, b for 1000 km distance.
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Copyr ight © CRC Pr ess LLC
by Abhijit S. Pandya; Ercan Sen CRC Press, CRC Press LLC
ISBN: 0849331390 Pub Date: 110198
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Chapter 2 Basic ATM Concepts
Asynchronous transfer mode ATM technology promises the integration of the diverse services of voice, video, image and data. ATM is a technology that allows transmission and switching of fixed-
length packets known as cells through an ATM switching network asynchronously. The fixed-length ATM cell structure defines the foundation of the ATM technology. This chapter provides a high-level
overview of ATM concepts.
I. ATM Overview
There has been a growing interest in the development of integrated multi-service enterprise and service provider networks, which consolidate voice, video, imaging, and computer data traffic into a single
network. The driving forces for this interest are the rapid rate of growth in non-voice traffic, the emergence of new strategic multimedia applications, and the significant cost savings which can be
realized from network consolidation. A common direction for both enterprises and service providers is the evolution towards ATM networking.
High-speed networks refer to networks with a link capacity of 100 Mbitss and above. They are also high capacity networks. If a large number of users are sharing the capacity, their behavior is not
fundamentally different from lower speed networks. However, in the case of a small number of high- bandwidth users the latency may start to dominate performance. Thus it is critical to reduce or hide end-
to-end latency. Table 2-1 lists various alternatives for high speed networking.
A principal attribute of ATM is that it is equally suitable for departmental and campus local area networks LAN, metropolitan area networks MAN and wide area networks WAN. In order to attain
the end-to-end integration of broadband services, interoperability of LANs, MANs and WANs is a key requirement. For the first time this one technology is positioned to provide an end-to-end solution for the
user.
Table 2-1
