|
Asynchronous transfer mode (ATM) is a
high-performance, cell-oriented switching and statistical
multiplexing technology that utilizes fixed-length packets to carry
different types of traffic. ATM is a technology that enables
carriers to capitalize on a number of revenue opportunities through
multiple ATM classes of services; high-speed local-area network
(LAN) interconnection; voice, video, and future multimedia
applications in business markets in the short term; and in community
and residential markets in the longer term.
Changes in the structure of the telecommunications industry and
market conditions have brought new opportunities and challenges for
network operators and public service providers. Networks that have
been primarily focused on providing better voice services are
evolving to meet new multimedia communications challenges and
competitive pressures. Services based on asynchronous transfer mode
(ATM) and synchronous digital hierarchy (SDH)/synchronous optical
network (SONET) or optical transport network (OTN) architectures
provide the flexible infrastructure essential for success in this
evolving market. Broadband network backbones exploit widely deployed
fiber-optic links to build highly available digital channels, based
on the SDH TDM or WDM transmission technology.
An early view was that the ATM networks would evolve in an orderly
way from the core out. In this idealistic environment high-speed ATM
core networks would be installed to accommodate each and every type
of application installed in the access networks. However, it rapidly
became clear that business pressures do not permit this orderly form
of evolution. Business applications require urgent implementation,
particularly in key new areas where “first to market” can make a
substantial difference to profitability and business success. The
cost-effective short-term solutions are being implemented, just to
first to market.
The need is now emerging for a more orderly approach to accommodate
the growing market need for interconnectivity between Internet
services, bulk data, imaging, transaction, video, and frame relay
applications. Also, many applications, particularly multimedia
applications, require sharing of processing, storage, and database
access functions across interconnected components in both public and
private networks.
ATM as the technology of public and private networks is now a
reality, with service providers around the world introducing and
rolling out ATM and ATM–based services. The ability to exploit the
benefits of ATM technology within the public network successfully
will provide strategic competitive advantage to carriers and
enterprises alike.
In addition to revenue opportunities, ATM reduces infrastructure
costs through efficient bandwidth management, operational
simplicity, and the consolidation of overlay networks. Carriers can
no longer afford to go through the financial burden and time
required to deploy a separate network for each new service
requirement (e.g., dedicating a network for a single service such as
transparent LAN or frame relay). ATM technology will allow core
network stability while allowing service interfaces and other
equipment to evolve rapidly.
The rest of this chapter is structured as follows. First ATM
concept, protocol stack, ATM networking are briefly reviewed. Later,
ATM applications as a common integrated multi-service platform and
its current role within the network and service providers are
discussed. Subsequently, the evolution towards ATM-based
transmission technology is reviewed and advantages or disadvantages
of an ATM based transport infrastructure are stated. Finally, after
a brief comparison between standard SDH TDM overlay network and the
ATM-based or IP-based alternative, the conclusions and future
directions in the industry, network operators and service providers
are pointed out.
|
