Is ATM the future of all global communications?
Much hype surrounds the so called 'information superhighway', but the
truth is, that the contemporary public telecommunication networks that
form this highway are currently a serious bottleneck. With an increase in
demand for broadband networking from businesses and a potentially
huge market for domestic teleservices, a global broadband solution may
well be needed. A new standard is catching on, namely ATM; but does
it offer a solution to all our global networking problems?
Arran Derbyshire, 27th May 1996
Points addressed in this article:
Changes in the global networking climate
The relative stability of telecommunications infrastructure experienced
by corporate and domestic users now seems to be coming to an end.
With corporate decentralisation and geographic dispersal, there is an
increasing demand for wide area networking in the business community.
Businesses have a choice of networks which provide a backbone on
which to build their infrastructure, but there is a current trend towards
using LAN's connected to public networks. This coupled with an
emerging domestic market for a range of teleservices suggests a
requirement for an adaptable broadband public data network.
The ATM network solution
Existing telecommunications networks have been dimensioned to
handle specific applications as they became identified by the
operating companies. This approach has a number of
associated disadvantages:
- Each network requires it's own implementation and
maintenance phases
- Service specialisation prevents the networks from
implementing other services efficiently or adapting to
changes in services
- Free resources available across networks will be
wasted because they cannot be assigned to other
services
The Asynchronous Transfer Mode (ATM) architecture has been designed
to address these problems and provide a high bandwidth network
solution for the future. The ATM principle was first recommended by the
CCITT* in 1988 to be the standard transfer mode for broadband
communications.
The general lowdown...
ATM is a packet oriented transfer mode based on time division multiplexing
capable of providing users high speed data traffic rates (multigigabit
datapipes have been proposed). The information is divided into 'cells'
(i.e. packets) and multiplexed asynchronously. This gives the system the
potential to transmit data of different natural rates and therefore different
bandwidths, over the same connection. This is the most important feature
of the ATM architecture, as it gives it the ability to support a wide range of
services on a single network.
*Now the ITU-T, following a
reorganisation of the ITU in 1993.
What can ATM offer to network users?
The service flexibility and high bandwidth of ATM networks could mean
that some attractive applications would become feasible or more available
to business and domestic users. Such domestic applications include:
- Digital TV and HDTV
- Video vending
- Videophony
With business applications including:
- High speed LAN interconnection
- Teleconferencing
- Multimedia electronic mail
At home...
A public ATM network could offer some entirely new services to people
in their homes. The most significant type of new services will be the
possible video services. What will be so unique about these services is
the opportunity for a viewer to interact more with the programmes they
receive. These types of applications will be the most demanding on the
technology, digital video uses the most bandwidth of the forseen
applications. Video data compression techniques, such as the MPEG
forms, have been developed to optimise the use of the networks.
At work...
The high speed LAN interconnection is the reaction that the business
community is likely to take to ATM. However, ATM has the potential
to carry all traffic that would normally be carried on WAN's and LAN's
- on a single network. This goes against the tradition of having slow
Ethernet LANs buckling under the strain of imaging and videoconferencing
applications. ATM could remove the WAN bottlenecks and the LAN
bottlenecks in one fell swoop.
Industrial applications of ATM include the networking of manufacturing
processes, with remote visual control or inspection distributed within
factories. Interest is developing in the medical community for using
ATM to distribute X-Ray images and other medical images in real time.
Corporate education could benefit by multimedia lecturing from the
employees being trained over a wide area, without having to travel.
Why should ATM become a key network technology?
From a business perspective, the current alternatives to the system
are frame relay, Fibre Distributed Data Interface (FDDI), X.25 and
Systems Network Architecture, which will all provide high speed
data communications. However, an increase in bandwidth demand
in the future is inevitable from the up and coming bandwidth hungry
multi-media applications, which will certainly exceed their dimensions.
Favourable trends
The public telecommunications companies follow ITU regulations,
so the public domain and businesses operating in it will be running
under the ATM system. There is a trend for private telecommunications
companies to align themselves to public standards, and ATM is likely
have a large influence there also. If businesses decide to operate on
these networks, there is a financial incentive to move over to ATM
earlier rather than later.
Survival of the fittest
Perhaps the main advantage ATM has over traditional networks is it's
ability to cope with services with a range of bandwidth requirements.
This makes it flexible and therefore future proof into the forseeable
future. The fact that all services could run on a single network, instead
of one network for each service, makes the setup and maintenance of
public ATM networks cost effective. Also, because the ATM system
shares the available network resources between services optimally,
further cost advantages are made from efficiency. Due to these
attributes, it is likely that ATM will out live most of it's contemporaries.
Big money
At present ATM services are available to businesses connected to
WAN's, but it doesn't come cheap. The high cost of ATM makes
other peer services seem more attractive, such as frame relay or
SMDS. However, the Vertical Systems Group, (a broadband
technologies consultancy firm) is predicting the market value of
ATM to be $2bn by 1998, compared to $134m in 1994. It seems
inevitable that ATM will eventually make telecommunications
companies a stack of money. The short term revenues of ATM will
only be through the transport of kilobit and megabit technologies,
such as older network protocols and even voice communications.
It will take time before ATM networks will be used to their
multi-gigabit potential.
Concluding remarks
ATM provides the chance for a universal network standard which could
provide wideband communications for public and private networks
globally. It has the capability to provide all the services provided by all
the other contemporary networks, but with eventual cost advantages
due to resource optimisation and infrastructure duplication minimisation.
It is being pushed by telecommunication industry authorities, and being
adopted by the data communications community. ATM could provide a
standard not only for WAN, but also for LAN as well.
The technology to provide wideband ATM communications has come
of age and the ATM system is proven. Now, the greatest barriers to
overcome are of the nature of economic and organisational. The
operating companies willing to move to ATM must convince the
corporate networking community that their expectations will be
reached. Perhaps more dramatically, the domestic users of public
networks must be convinced that they need the services which
broadband networks can offer.
If the move to ATM is made on a large scale, then multimedia rich
applications may well be on networks available to consumers
world wide. This could mean a multimedia work place and a
large array of high quality teleservices at home. Certainly, surfing
the net would never be the same again...
Bibliography
ASYNCHRONOUS TRANSFER MODE Solution for Broadband ISDN
2nd Edition, Martin de Prycker, Ellis Horwood Publishing.
"The Lines Unleashed" in Byte - May 1996, plus articles: "The New WAN"
by Salvatore Salamone, "The Price of WAN Connectivity" by Liza Henderson
and "Playing the ATM Card" by Lane F. Cooper.
"Asynchronous transfer mode: the ultimate broadband solution?"
by M. Jeffrey, Electronics & Communications Engineering Journal
June 1994.
"Management of patient records with NHS local area supported by ATM" by
Constantinos TSIBANIS, Department of Computer Science at Bristol.
Abbreviations
- ATM
- asynchronous transfer mode
- CCITT
- Consultative Committee for International Telecommunications and Telegraphy
- HDTV
- high definition television
- ISDN
- integrated services digital network
- ITU
- International Telecommunications Union
- ITU-T
- ITU Telecom Standards Sector
- LAN
- local area network
- MPEG
- Moving Pictures Expert Group
- N-ISDN
- narrowband-ISDN
- SMDS
- switched multimegabit data service
- WAN
- wide area network
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