February 1999

Gatekeepers - Conducting The IP Symphony

BY LIOR HARAMATY

In most features, we avoid running vendor-specific material. However, for articles directed at the Internet telephony developer community, a less generic and more nuts-and-bolts approach seems appropriate. Of course such an approach is by its very nature more vendor-specific. To help readers distinguish between ordinary features and development-oriented features, we run the latter under the heading Developer's Corner.

Gatekeepers are creating a seismic shift in the Internet telephony industry. By serving as the intelligent control point for Internet telephony networks, gatekeepers are transforming a technology once thought of as synonymous with low cost international phone calls into a platform for a new era in communications. But just what are gatekeepers and why are they essential components for Internet telephony networks?

NEW MARKET COMPETITION
Before detailing the need for gatekeepers, the rise of the Internet telephony industry needs to be put in proper perspective. The telecommunications industry is currently undergoing a massive transformation due to larger industry forces, namely deregulation and globalization, resulting in increased competition and rapidly dropping calling rates. To compete in this new market, carriers need lower cost, lower maintenance, and more efficient networks to support calling plans.

Coinciding with declining calling rates is the increase in the number of sophisticated users and dispersed global operations demanding more powerful communications solutions. Although the PSTN is a reliable and stable network, it is not conducive to the addition of a new generation of communications services. Upgrades are expensive and complicated because the intelligence of the PSTN is buried in the center of the network. Legacy networks are also based on proprietary technology that inhibits rather than inspires the entrepreneurial development of new applications.

WHY IT WORKS
As a result of this changing marketplace, Internet telephony is emerging as a dominant platform for communications. According to James Crowe, CEO at Level 3 Communications, Internet telephony can provide voice services for 1/27th the cost of today's circuit-switched networks. Savings are achieved through toll-bypass, lower equipment costs, and greater network efficiency.

But with call rates dropping, carriers and corporations need more than lower rates to achieve an advantage over their competition. Here is where the true value of Internet telephony lies. By supporting open standards and the convergence of voice, video, and data, Internet telephony provides an ideal medium for new multimedia and advanced communications applications.

Recognizing the advantages of this new technology, carriers and corporations began to deploy Internet telephony networks. Early networks consisted of scattered gateways linking the PSTN and IP networks, supporting limited phone-to-phone and PC-to-phone services. Driven by the growth of corporate and carrier networks and the entrance of progressive major carriers, such as Deutsche Telecom, it became clear that gateways alone were not sufficient to enable global services.

Manageability and scalability were at the heart of the problem. Early gateways contained all the network intelligence, and as a result, all changes and upgrades in an Internet telephony operation (such as the addition of new users or services) had to be made one by one on each gateway. It proved physically impossible for a network administrator to effectively configure each individual gateway in a global Internet telephony network to accurately track, bill, secure, and route traditional and multimedia traffic flowing among thousands of gateways and specialized servers - connecting millions of users calling from traditional telephones, PCs, and other intelligent end unit devices.

GATEKEEPERS TO THE RESCUE
Gatekeepers are the intelligent elements that bring sophisticated management capabilities to IP networks for commercially viable services. By serving as the chief control center, gatekeepers allow managers to grow their networks gradually, starting from a limited rollout of low cost phone-to-phone service that can scale to meet a global customer base and support new services. Gatekeeper functionality can include:

• Authentication and authorization of users;
• Authentication and authorization of network elements, such as telephony gateways;
• Call routing, determined by factors such as quality of service (QoS), communication media capabilities, and user ID;
• Least cost routing;
• Load balancing;
• Accounting and call log capabilities;
• Address resolution; and
• Call forwarding to a variety of endpoint devices like pagers, fax machines, and PCs.

One such intelligent element - the VocalTec Gatekeeper - acts as the brains of the network, threading traditional and mixed media calls through gateways and specialized servers dispersed in multiple domains all over the world. It includes an Accounting, Authorization and Authentication Applications Program Interface (AAA API) layer, enabling carriers and service providers to open up their networks to preferred billing and security solutions. This API layer allows for the integration of new enhanced services into the network, such as several levels of QoS. It also allows for integration into SS7 networks. The Gatekeeper works in conjunction with the VocalTec Network Manager to give network administrators the ability to configure gateways, servers, and endpoints from a single interface.

The Gatekeeper is also capable of advanced address resolution functions that enable it to resolve dynamic IP addresses and PSTN numbers. Its flexible management features allow communications networks to recognize users with a new level of intelligence. Today's communications users are challenged by a revolving door of calls to their home and work numbers, pagers, cell phones, and PCs. The Gatekeeper can reduce these numbers to a single virtual identity, and direct calls to an end unit device designated by the user.

NETWORK TOPOLOGY
The Gatekeeper is an important part of the VocalTec Ensemble Architecture (VEA), a standards-based platform for global Internet telephony services. This architecture is designed to maximize the capabilities of the Gatekeeper in conjunction with other network components including gateways, specialized servers, network managers, and other gatekeepers. In a VEA environment, the Gatekeeper is the genie of the communications service. It acts as the grand orchestrator of all services by fielding queries from the other Internet telephony network components regarding the direction, tracking, and billing of traffic.

For example, the gateway would receive an incoming call from an endpoint (either a PC or telephone), forward the call to the gatekeeper, and act according to the Gatekeeper's instructions. The Gatekeeper would track the call from the beginning to the end, and reference programs plugged into its AAA API layer to assure that users are authorized, authenticated, and accurately billed for services such as video, QoS, and conference calls. The Gatekeeper would perform address functions resolving a virtual identity with a user designated endpoint, connecting dynamic IP addresses to regular phones, and opening up calls to incorporate specialized server capabilities such as multipoint audio and data conferencing. Multiple Gatekeepers make up a single network to support the growth of increased traffic and redundancy - and in case of a gatekeeper failure - to maintain uninterrupted service.

We can think of two examples of VEA-based network topology. The first exemplifies a simple single service provider network, where authentication, authorization, billing, network control, and network monitoring are all done in one central location using the Network Manager in conjunction with the Gatekeeper.

The second exemplifies an intradomain network with multiple service providers. With only limited information revealed between domains, calls would be terminated between providers and billing created across the board.

SUPPORTING THE STANDARDS
The maturity of international standards and their evolution toward service-oriented views continues to be one of the most important factors driving growth in the Internet telephony market. Standards-based technologies make wide-scale deployment possible, giving customers the freedom to choose the best solution from a field of competitors. Without open standards, networks are no more than "islands" of communication, dependent on a single vendor and inhospitable to new solutions.

The Gatekeeper is defined by the International Telecommunications Union (ITU) H.323 standard. H.323 is the leading industry standard for shipping products, and VocalTec pushed the H.323 recommendation in its second version toward greater scalability, network intelligence, and security, known as H.323 Registration, Administration, and Status (RAS) Version 2.

As an H.323-compliant system, VEA supports Simple Network Management Protocol (SNMP). By doing so, network administrators can manage and monitor all nodes on their IP network including Internet telephony gateways and gatekeepers. VEA is manageable from any SNMP-compliant platform such as HP OpenView.

In order to enable carriers and corporations to build multivendor Internet telephony networks while standards are still in development, VocalTec has been developing interoperability based on H.323 between its Internet telephony product suites and those of Lucent, Ascend, and Cisco.

Internet telephony is no longer about cheap phone-to-phone services - it's about the advanced services that can be supported. In order to realize this value, Internet telephony networks must have the intelligence and management functions that gatekeepers deliver. Providing standards-based end-to-end solutions is critical. Complete solutions that support global enhanced services, and interoperate with other leading Internet telephony vendors, will enable corporations and carriers to use Internet telephony to communicate and compete more effectively today and in the future.

Lior Haramaty is vice president of technical marketing and a co-founder of VocalTec Communications. VocalTec develops and markets end-to-end communications solutions for service providers, corporations and individuals. The company's systems are used worldwide for voice, video, data, and fax communications over the Internet, telephony networks, and private networks to improve productivity and reduce telecommunications costs. For more information about the company and its products, please visit their Web site at www.vocaltec.com.