All-digital Network Research Articles

A Brief History of AT&T's First Digital Signal Processor: Technology Challenges in Its Development

In the early 1970s, Bell Labs was preparing the foundation for revolutionizing the Bell System network. For nearly 100 years, the telephone system relied on transmitting and switching analog signals. With the advent of large-scale integrated (LSI) circuit technology, the future was an all-digital network. The pace of development was picking up, and flexibility and time to market were increasingly important.

Taxonomy and Survey of Collaborative Intrusion Detection

The dependency of our society on networked computers has become frightening: In the economy, all-digital networks have turned from facilitators to drivers; as cyber-physical systems are coming of age, computer networks are now becoming the central nervous systems of our physical world—even of highly critical infrastructures such as the power grid. At the same time, the 24/7 availability and correct functioning of networked computers has become much more threatened: The number of sophisticated and highly tailored attacks on IT systems has significantly increased. Intrusion Detection Systems (IDSs) are a key component of the corresponding defense measures; they have been extensively studied and utilized in the past. Since conventional IDSs are not scalable to big company networks and beyond, nor to massively parallel attacks, Collaborative IDSs (CIDSs) have emerged. They consist of several monitoring components that collect and exchange data. Depending on the specific CIDS architecture, central or distributed analysis components mine the gathered data to identify attacks. Resulting alerts are correlated among multiple monitors in order to create a holistic view of the network monitored. This article first determines relevant requirements for CIDSs; it then differentiates distinct building blocks as a basis for introducing a CIDS design space and for discussing it with respect to requirements. Based on this design space, attacks that evade CIDSs and attacks on the availability of the CIDSs themselves are discussed. The entire framework of requirements, building blocks, and attacks as introduced is then used for a comprehensive analysis of the state of the art in collaborative intrusion detection, including a detailed survey and comparison of specific CIDS approaches.

Early T-carrier history

In the 1950s ATT the solutions were found and incorporated into a new system design. The product was T-Carrier, which was introduced into service in 1962. This new application of PCM was highly successful and the technology was licensed to the independent telephone industry. The race toward an all-digital network of digital transmission and switching was off and running.

All-digital network transmission planning and terminal requirements

The development of a proposed transmission plan for an all-digital network is described. The main objectives of the plan are to obtain optimum end-to-end loudness grade-of-service, bit transparency, and echo control on all-digital connections and to ensure adequate transmission performance on hybrid connections, i.e. mixed analog/digital. These objectives are met by migrating connection loss, traditionally applied in the network, to the analog side of the digital/analog interface in the digital terminal. Thus the network transmission plan and digital access terminal characteristics are strongly interrelated. The proposed plan provides additional advantages including elimination of switched losses in the network when digital terminals are used and easy interconnection between networks (public and private).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Transition to the AT&amp;T-IS Integrated Private Network Architecture

Private corporate networks are evolving toward all-digital networks that combine voice and data transmission on a single network. The functional and economic advantages of those networks over their analog antecendents motivate this evolution. This paper describes AT&T Information Systems integrated private network architecture and its functional and economic advantages.

Transmission loss planning for digital networks

AbstractThis paper describes the transmission loss plan for a digital network on the basis of transmission quality evaluation data for telephone, modern and facsimile services. First, reference equivalent distribution of a subscriber loop and terminal return loss distribution at 2‐wire/4‐wire conversion circuit of digital local exchange subscriber circuit, which are network parameters for transmission loss planning, are estimated based on investigations of the actual conditions. Next, with respect to the telephone, the relation between transmission loss and opinion is clarified both for a short length of connection where degradation due to echo is negligible and for medium and long length of connections where the echo performance is taken into account. With respect to modem and facsimile, the relation between openloop loss and quality degradation is evaluated experimentally. As a result of total evaluation of network parameters and evaluation data with respect to telephone, modem and facsimile, it is revealed that the transmission loss in EO‐EO all‐digital network should be set at 4 dB for intra‐office connecnection. Here, degradation due to echo is negligible and 8 dB for medium and long length of connections where echo performance is taken into account to maintain good telephone and modem‐facsimile transmission quality. Finally, the transmission loss plan from existing analog network to EO‐EO all digital network is shown.