02-01-2013, 10:38 AM
Convergence of Telecommunications and Computing to Networking Models for Integrated Services and Applications
[attachment=46092]
ABSTRACT
This paper gives a snapshot of the convergence of the
telecommunications and computer industries to a common vision
of networking models for an integrated services information
infrastructure meeting the stringent requirements of multimedia
applications.
At first, we summarize the requirements and elements of such
an infrastructure and introduce a networking model that is framed
into four layers: interconnection (bearer), internetworking,
interoperability (middleware), and application. Then, we offer
a brief review of the classical telecommunications networking
model, the current status of asynchronous transfer mode (ATM)
multimedia networking features, and the ongoing activities for
fostering evolution of telecommunications networks to enhance
control, management, and service delivery. An overview of the
current Internet network architecture follows, presenting the
recent achievements and the evolving networking protocols to
cope with real-time multimedia applications.
As described in this paper, the schemes for integrating
Internet protocols (IP’s) and ATM resource reservation protocols,
which address an efficient resource utilization and quality of
service guarantee in broad-band networks, fall into the first two
lower architectural layers, which are the foundation of network
computing and communications services. In particular, we present
a summary description of the comparative features of both IP and
ATM protocol approaches, and we report on current proposals
for provisioning IP on ATM networks.
INTRODUCTION
Considerable research effort is devoted to pursuing the
promise of the information highway, that is, a high-speed,
ubiquitous, and seamless integrated services information
infrastructure [1]. The classical telecommunications and
computer networking paradigms fail to support adequately
all the emerging requirements of such an ambitious project.
The next years will be devoted to enhancing current system
networking architectures in order to cope with these
evolving needs.
For many years, the commitment of telecommunications
companies to the bare transport of information, by means of
digital transmission and switching facilities, has expanded
its scope by enhancing network control and management capabilities.
The emphasis of upcoming telecommunications
networks is on multimedia distributed services, and operators
are exploring technologies and network architectures
capable of offering value-added network-centric services.
Starting from the basic concept of the IN [2], [3], the ITU-T
standards committees and other telecommunications-related
fora, such as the TINA consortium [4]–[6], propose service
control and management architectures and technologies.
ATM is the technology designed for connection-oriented
transport of information in high-speed networks, in both
wide and local areas [7], [8].
TELECOMMUNICATIONS
Classical Architecture
Telecommunications have developed during this century
under the paradigm of POTS. Access to POTS is obtained
via an inexpensive and dumb appliance, the phone station
(powered by the network), that has the double purpose of
controlling the call routing (signaling) and transporting the
voice signals to and from the called end user by means of
a rather simple and friendly user interface. POTS network
switching nodes have the same double function, namely,
the interchange of signaling messages between switches
and the phone stations and the routed transport of voice
signals through the network.
The business model is based upon a contract between any
user (service subscriber) and the service/network provider.
The caller is paying for the call on the basis of the call
duration and geographical distance of the called entity. The
contract guarantees that the probability of blocking any
call because of network design or malfunction is very low,
say, around 1%, and the established circuit offers constant
bandwidth and constant low latency for the entire duration
of the call to the end users. POTS service quality and
availability are maintained through the worldwide network
at very high-level standards.
ATM Networks
For the information access and transport technologies, the
progress of digital transmission and switching technologies
has enabled the development and deployment of integrated
services broad-band networks. Broad-band network
backbones exploit widely deployed fiber-optic links to
build highly available digital channels, based on the SDH
transmission technology. The broad-band access network
architecture is one of the critical components in the delivery
of digital broad-band services. HFC [41] and ADSL [42]
are regarded as the more promising alternatives in the last
mile, though wireless and satellite technology will play a
key role in this network segment. ATM, though, in spite
of the slow market penetration, is the flag of emerging
information-transfer techniques conceived for broad-band
telecommunications networks. In the ATM-based B-ISDN,
all forms of user traffic are segmented into uniform data
units of small size and routed through the switching nodes
and transmission links of the network. The users would
have bandwidth on demand, and the underlying network
would be based upon a single switching and multiplexing
principle. This capability has been viewed as especially
important for multimedia services, where a given call may
contain voice, data, and video information.
Connections and Datagrams
For many years, among the services offered by telephone
companies, the data-communications service was of the
connection-oriented type only. Connection-oriented types
of data communications were adopted starting from ITU
recommendation X.25 [67], extending to FR [46], and
finally being adopted also in ATM networks. In contrast,
datagrams and connectionless transfer modes have been
at the core of computer communications, including LAN
communications and the Internet. The terminology itself
is biased toward the notion of connections (may we call
them datagramless communications?). Datagram communications
are finally being introduced in telecommunications
networks [68], however: the SMDS [69] and the proposed
ATM fast resource management feature [70] to transfer
datagrams in ATMnetworks are two significant examples of
the recent interest of the telecommunications community in
connectionless communications. Last, the growing interest
in the Internet has put enormous emphasis on the transport
of the connectionless protocol par excellence, IP, over
connection-oriented ATM networks [71] (see Section IV).
Distributed Processing
The idea of intermediate software tools and platforms,
the middleware, for supporting application development
in a heterogeneous, distributed processing environment
was born in the 1980’s. An important characteristic of
these platforms is their support for logically integrated
but physically distributed systems. Moreover, the same
platform can span different operating systems, allowing the
creation of heterogeneous architectures. To facilitate the
development of tools that can be integrated in the existing
platform, the mechanisms that assure interoperability are
being standardized.
[attachment=46092]
ABSTRACT
This paper gives a snapshot of the convergence of the
telecommunications and computer industries to a common vision
of networking models for an integrated services information
infrastructure meeting the stringent requirements of multimedia
applications.
At first, we summarize the requirements and elements of such
an infrastructure and introduce a networking model that is framed
into four layers: interconnection (bearer), internetworking,
interoperability (middleware), and application. Then, we offer
a brief review of the classical telecommunications networking
model, the current status of asynchronous transfer mode (ATM)
multimedia networking features, and the ongoing activities for
fostering evolution of telecommunications networks to enhance
control, management, and service delivery. An overview of the
current Internet network architecture follows, presenting the
recent achievements and the evolving networking protocols to
cope with real-time multimedia applications.
As described in this paper, the schemes for integrating
Internet protocols (IP’s) and ATM resource reservation protocols,
which address an efficient resource utilization and quality of
service guarantee in broad-band networks, fall into the first two
lower architectural layers, which are the foundation of network
computing and communications services. In particular, we present
a summary description of the comparative features of both IP and
ATM protocol approaches, and we report on current proposals
for provisioning IP on ATM networks.
INTRODUCTION
Considerable research effort is devoted to pursuing the
promise of the information highway, that is, a high-speed,
ubiquitous, and seamless integrated services information
infrastructure [1]. The classical telecommunications and
computer networking paradigms fail to support adequately
all the emerging requirements of such an ambitious project.
The next years will be devoted to enhancing current system
networking architectures in order to cope with these
evolving needs.
For many years, the commitment of telecommunications
companies to the bare transport of information, by means of
digital transmission and switching facilities, has expanded
its scope by enhancing network control and management capabilities.
The emphasis of upcoming telecommunications
networks is on multimedia distributed services, and operators
are exploring technologies and network architectures
capable of offering value-added network-centric services.
Starting from the basic concept of the IN [2], [3], the ITU-T
standards committees and other telecommunications-related
fora, such as the TINA consortium [4]–[6], propose service
control and management architectures and technologies.
ATM is the technology designed for connection-oriented
transport of information in high-speed networks, in both
wide and local areas [7], [8].
TELECOMMUNICATIONS
Classical Architecture
Telecommunications have developed during this century
under the paradigm of POTS. Access to POTS is obtained
via an inexpensive and dumb appliance, the phone station
(powered by the network), that has the double purpose of
controlling the call routing (signaling) and transporting the
voice signals to and from the called end user by means of
a rather simple and friendly user interface. POTS network
switching nodes have the same double function, namely,
the interchange of signaling messages between switches
and the phone stations and the routed transport of voice
signals through the network.
The business model is based upon a contract between any
user (service subscriber) and the service/network provider.
The caller is paying for the call on the basis of the call
duration and geographical distance of the called entity. The
contract guarantees that the probability of blocking any
call because of network design or malfunction is very low,
say, around 1%, and the established circuit offers constant
bandwidth and constant low latency for the entire duration
of the call to the end users. POTS service quality and
availability are maintained through the worldwide network
at very high-level standards.
ATM Networks
For the information access and transport technologies, the
progress of digital transmission and switching technologies
has enabled the development and deployment of integrated
services broad-band networks. Broad-band network
backbones exploit widely deployed fiber-optic links to
build highly available digital channels, based on the SDH
transmission technology. The broad-band access network
architecture is one of the critical components in the delivery
of digital broad-band services. HFC [41] and ADSL [42]
are regarded as the more promising alternatives in the last
mile, though wireless and satellite technology will play a
key role in this network segment. ATM, though, in spite
of the slow market penetration, is the flag of emerging
information-transfer techniques conceived for broad-band
telecommunications networks. In the ATM-based B-ISDN,
all forms of user traffic are segmented into uniform data
units of small size and routed through the switching nodes
and transmission links of the network. The users would
have bandwidth on demand, and the underlying network
would be based upon a single switching and multiplexing
principle. This capability has been viewed as especially
important for multimedia services, where a given call may
contain voice, data, and video information.
Connections and Datagrams
For many years, among the services offered by telephone
companies, the data-communications service was of the
connection-oriented type only. Connection-oriented types
of data communications were adopted starting from ITU
recommendation X.25 [67], extending to FR [46], and
finally being adopted also in ATM networks. In contrast,
datagrams and connectionless transfer modes have been
at the core of computer communications, including LAN
communications and the Internet. The terminology itself
is biased toward the notion of connections (may we call
them datagramless communications?). Datagram communications
are finally being introduced in telecommunications
networks [68], however: the SMDS [69] and the proposed
ATM fast resource management feature [70] to transfer
datagrams in ATMnetworks are two significant examples of
the recent interest of the telecommunications community in
connectionless communications. Last, the growing interest
in the Internet has put enormous emphasis on the transport
of the connectionless protocol par excellence, IP, over
connection-oriented ATM networks [71] (see Section IV).
Distributed Processing
The idea of intermediate software tools and platforms,
the middleware, for supporting application development
in a heterogeneous, distributed processing environment
was born in the 1980’s. An important characteristic of
these platforms is their support for logically integrated
but physically distributed systems. Moreover, the same
platform can span different operating systems, allowing the
creation of heterogeneous architectures. To facilitate the
development of tools that can be integrated in the existing
platform, the mechanisms that assure interoperability are
being standardized.