Mounting requests for advanced services and faster deployment have compelled public network service providers to affix adjunct programmable switching platforms to their networks for quick prototyping and implementation of enhanced communications applications. Programmable switching fabrics provide easy network connectivity--via T1 or E1 spans, for example--while giving service providers greater freedom from being dependent solely on switch vendor development cycles.
In the interest of establishing competitive advantage, service providers have been a driving force in the use and evolution of the programmable switch. Venture Development Corp., in a 1996 survey, revealed 53 percent of providers had programmable switches in 1995, with 97 percent expecting to add them to their inventory by 2000. Venture predicted that worldwide shipments of enhanced service platforms will increase by 340 percent over 1993 statistics to exceed $10 billion in 1998. With usage projected to more than triple, programmable switches have, indeed, evolved from simple add-on supplements to fundamental network components.
The Programmable Evolution
Dating back to the early 1980s, programmable switching initially was used as an adjunct to telco local exchange networks, controlling message distribution and introducing new routing and management functions to the network. The divestiture of AT&T and the introduction of equal access in 1984 served as catalysts for a growing interexchange carrier (IXC) market. Equal access enabled subscribers to place long distance calls with the IXC of their choice through presubscription (1+ dialing). With 1+ dialing spurring competition, IXCs looked to introduce new enhanced services as a primary differentiator. This rapid change in the telecom industry encouraged expeditious release of new services and set the stage for the evolution of a network infrastructure in which the programmable switch would play an elemental role.
Another noteworthy predecessor of today's programmable switch followed four years later. In 1988, federal approval of a petition from the Bell companies to offer voice storage and electronic mail services opened the door to the voice processing market. Communications manufacturers began in earnest to produce a programmable switching product capable of deploying enhanced voice services.
Two years later, equal access for enhanced services met federal regulatory approval. Open network architecture was so named by the Federal Communications Commission (FCC) because it permitted all types of terminals and users to access the public network. Using an open, standard interface specification, it enabled providers of enhanced services to obtain basic network functions and interfaces from local exchange carriers (LECs) on an unbundled basis. Open network architecture, coupled with universal network interfaces, provided the framework for today's programmable switching products.
In the years following, several federal court decisions allowing regional Bells to market enhanced switching services encouraged the development of the programmable switch. In this environment, programmable networking interfaces soon began to surface as potent competitive solutions for enhanced service deployment. Service providers, such as LECs, IXCs and alternative local carriers were eager for the programmables' attributes because call processing power could be redistributed onto smaller, supplemental platforms that enabled faster service deployment with cost-reducing effects. In addition, a common user interface--one host program could accommodate a variety of operating systems--permitted easy interoperability.
Programmable as a Definitive Advantage
Today, most major carriers use some form of programmable switch fabric in their networks to provide a variety of enhanced and intelligent networking (IN) subscriber services. Before the programmable switch, switch-based services were wholly dependent on switch vendor development timetables. Providers were caught between long lead-times (typically a one-year development cycle) and a rapidly evolving, highly competitive marketplace, wherein new service creation and packaging could provide definitive advantages and enhance branding initiatives. Providers turned to the programmable switch to augment switch vendor features and meet the needs of their subscribers on a more timely basis.
Dubbed dumb because they have no means to execute their programs--but remain static until prompted into action by an external system--the programmables' intelligence comes from the application software running on an off-board host controller. Applications run the gamut from debit cards, voice mail, personal communications services (PCS) and voice-activated menu services to international callback functionality. Because programmable switches use PC-based external systems for call control, they allow carriers to program and release new enhanced services on a more rapid and customized basis than is frequently possible via switch vendor processes.
Adjunct programmable switching applications benefit every class of telecommunications company, from competitive LECs to global super carriers. One diversified operator services company that has used programmable switching to compete successfully in its niche market is Network Operator Services (NOS). NOS, with headquarters in Longview, Texas, is a telecommunications service provider that has used programmable switching fabrics to enhance basic service packages, including customized greetings, online transfer of callers to multilingual operators, emergency call handling, conference calling and instant online credit for customer misdials.
Peter R. Pattullo, chief technology officer, NOS, credits the programmable switch for the company's success in its niche market. "By fully externalizing call control on an off-board processing system, programmable switches allow us to take advantage of high-level programming languages and advanced software development tools to differentiate our enhanced services."
A programmable switch essentially consists of network interface cards, a switch matrix, signal processing cards, a motherboard containing a microprocessor and various other information processing equipment. Its abilities are dependent on the extent of its external controller's application software. Typical capacities of programmable switches today are about 2,000 ports per switch.
To date, programmable switches have been employed in two modes: stand-alone (used mostly by service bureaus for reselling enhanced services to other carriers) and overlay (used in traditional switch networks to trunk calls to enhanced service platforms). Uses for this customizable adjunct are as boundless as the imagination. It is this same expanse, nonetheless, that diminishes a network's performance and efficiency. As the number of applications introduced increases, so does the need for an increased number of programmable switches to support such additional enhanced solutions. As more of these overlays are integrated into a backbone structure, network management becomes more complex and potential performance issues result. Thus, service providers need to monitor network performance closely to attain value from their programmable switching network.
The Programmable Evolution Continues
One networks solutions supplier confronting industry dynamics and the role a programmable infrastructure can play is Nortel (Northern Telecom), based in Richardson, Texas. Nortel's DMS-Programmable Services Architec-ture (PSA)--introduced last June--represents a new service architecture that adds an integration mode to the programmable switching fabric and increases scalability up to 100,000 ports, enabling carriers to create, test, trial and deploy new services more rapidly.
The Nortel DMS-PSA is a product family comprising the DMS-Program-mable Services Node (PSN), NEBS-compliant ServiceLink Service Control Unit (SCU) and ServiceLink Media Resource Unit (MRU), and ServiceLink Applications Programming Interface (API). Modular and fully redundant, the DMS-PSA provides tremendous service creation flexibility while offering scalability, reliability and robustness--attributes consistent with large-scale, public network applications.
In the integrated mode, DMS-PSA gives service providers the capability to incorporate programmable service functionality with two of Nortel's switching systems (DMS-250 SuperNode tandem and DMS-500 local/long-distance switching systems). The new architecture selectively passes control of call processing and in-switch resources to an off-board processor, while retaining use of a portion of the switch for normal call handling. This hand-off eliminates the need for separate, stand-alone programmable switches in the network and provides a more robust architecture for network efficiency and performance.
Incorporating a common tool set and graphical user interface (GUI), DMS-PSA gives service providers options to create new enhanced service applications themselves, via third party developers, or even through Nortel's development resources. As a result, they can assume much greater control over their own service development, speed market deployment and aid in market differentiation. In addition, because DMS-PSA shares a common service creation environment (SCE) with Nortel's SCP product family, service providers can achieve maximum utilization from their existing SCP investment in terms of reducing incremental costs for network infrastructure and training, while optimizing their network administrators' operational experience.
"We recently installed the Nortel DMS-Programmable Services Architec-ture, which NOS believes takes programmable switching to a whole new plateau of reliability and scalability," NOS' Pattullo says. "PSA makes a tremendous difference in our network development. It allows us to simplify our future enhanced service platform requirements, giving us even greater, cost-effective control. In addition, because our customers' needs are foremost, PSA gives us an added advantage in responding to their service needs."
A Programmable Foundation
A public carrier's success clearly depends on subscriber satisfaction. With more providers placing increased importance on customer dialogue and partnering, PSAs will help them keep pace with burgeoning network demands. This translates to competitive advantages in the race for market share.
Michael Doerk, senior manager, IN Brand Management, Nortel, can be reached at (972) 684-1000.
