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February 1999


CompactPCI - The Open Road To Internet Telephony

BY POCHENG SHYU

While open systems continue to make inroads in practically every area of enterprise computing, it's ironic that the comparatively new area of Internet telephony has remained one of the last proprietary system strongholds. Now, due to the evolution of open bus architectures, this is rapidly changing.

It's not as if the pros and cons of open versus closed systems aren't clearly defined. Proprietary systems are plagued with significant footprint issues, and upgradability problems abound. Exorbitant long-term costs, limited product choice, and all the other negatives that revolve around vendor lock-in combine to paint a decidedly negative portrait of proprietary solutions. Once you commit to a proprietary system, you are committed to dealing with these negatives for a long, long time.

The open systems side presents a much more attractive picture. You can source from multiple vendors and select from a wide variety of computing platforms and widely adopted operating systems. Vendor lock-in is virtually a non-issue, and both immediate and long-term costs are considerably lower as a result. Integration with other enterprise systems (which are also increasingly likely to be open) is considerably easier, while easy upgradability is central to the open system paradigm.

OPEN SYSTEMS GAIN TRAFFIC
So why haven't lower-cost, more flexible, off-the-shelf PC-based systems overthrown proprietary solutions from the Internet telephony space? It largely comes down to a matter of bus architectures. You need to base such systems on a robust architecture capable of providing telephony's requisite reliability and scalability. The industry standard PCI local bus architecture provides all the benefits of using low-cost PC silicon including compatibility with thousands of PC software programs. Yet it does not make up for the poor thermal features, inadequate shock and vibration characteristics, and difficult serviceability of PC-based equipment - problems that most proprietary solutions are designed to avoid entirely.

One possible solution would be to take a page from embedded industrial applications, many of which are based on the VME bus architecture. VME, which is excellently suited for real-time applications, has reigned as the leading industrial bus architecture since 1984. While there is little question of VME's robustness - much of which is due to its Eurocard form factor - it has only a limited presence in the telephony marketplace, and is primarily found only in telephony central office applications.

A much more viable solution for Internet telephony can be found in the CompactPCI architecture. Though a relative newcomer, the use of CompactPCI is growing explosively, particularly in telecommunications markets. One of CompactPCI's biggest advantages for Internet telephony is that it is PCI's industrial computing extension. It delivers PCI's true processor independence (i.e., best silicon support), direct access to low-cost PC components and peripherals, 132 Mbps bandwidth for each bus segment, and a wealth of plug-and-play PC software. Applications can be developed on PC systems and then deployed unchanged on CompactPCI - something that can't be done as easily on proprietary systems.

The other major advantage of CompactPCI for Internet telephony is what it has borrowed from the venerable VME bus - namely industrial-strength reliability. CompactPCI uses VME's proven Eurocard form factor and adds several key embellishments to make it a particularly attractive architecture for mission-critical telephony applications. This, combined with its open PCI heritage and support for multiple hardware platforms, has led CompactPCI to be widely supported by all major telephony application vendors. As a result, there is no lack of cost-effective, off-the-shelf solutions waiting to be deployed on CompactPCI systems.

GOING THE EXTRA MILE
CompactPCI is designed to extend the advantages of the off-the-shelf PC model into critical environments such as Internet telephony. Up to seven CompactPCI slots can be designed into the primary PCI bus and multiple independent backplanes can be supported. This allows for considerably more expansion than the three slots typically supported by standard PCI bus technology.

In addition, CompactPCI implementations are based on a passive backplane configuration. When a CompactPCI card is removed, there is no significant impact on the rear I/O connections or on neighboring cards. Nor is there any internal cabling for card, motherboard, and other peripherals, so servicing is much easier. The CompactPCI controller is one slot on the CompactPCI bus, and is thus easy to pull out and replace when making repairs or when upgrading the system. Hot swapping of expansion cards is also supported, which dramatically decreases the downtime of an Internet telephony application.

CompactPCI cards are designed to work in a standard 19" rack, featuring front-panel insertion and removal, and front or rear panel I/O functionality. Their shock- and vibration-resistant Eurocard format supports CompactPCI's extensive "board keying" capabilities (up to 4,096 combinations), while card guides ensure rear backplane connector alignment. Unlike the chassis configuration used by most conventional PCs, the Eurocard format ensures an even airflow and minimizes the danger of heat buildup, which is, of course, a leading cause of board warpage and mechanical problems. Also, unlike standard PCs, CompactPCI implementations use rugged 2-mm hard metric pin and socket connectors (ANSI IEC-1076) designed for use in telecom equipment.

Finally, CompactPCI's 6U (long card) form factor provides a higher degree of I/O functionality, a larger number of I/O ports, and more I/O pins than standard PCI-based systems.

A BUS THAT DELIVERS
Companies looking to implement robust open Internet telephony solutions today will find highly expandable CompactPCI systems available from several vendors. Systems can be configured using off-the-shelf cards and peripherals to suit a variety of applications - from call centers and T1 applications to Internet telephony gateway platforms and voice/fax over IP. These solutions can be based on a choice of the most popular hardware architectures, including Pentium, SPARC, and PowerPC. CompactPCI also supports MIPS, Alpha, and a variety of specialty microprocessors.

It is also possible to implement CompactPCI solutions with an integrated industry-standard H.110 computer telephony bus. H.110 on CompactPCI provides seamless interoperation of components by facilitating time division multiplexing directly on the system backplane.

Companies can easily build an application-ready system on this base using off-the-shelf components, with very little in the way of engineering design cycles and costs. For example, high-density dual backplane systems are already on the market to provide up to 14 6U CompactPCI expansion slots with an integrated H.110 bus. CompactPCI cards are readily available from leading vendors such as Dialogic and Natural MicroSystems to populate these slots and complete a multiple-resource system. An easily assembled basic configuration would include a voice encoder board, T1/E1 telecom board, and an IP network board to connect a LAN or WAN. A more complete Internet telephony system can add additional off-the-shelf components such as a real-time fax over IP board, an ATM or frame relay board, an automatic speech recognition or voice response board, and more.

Unlike open systems based on the standard PCI bus - or on ISA or EISA bus architectures - these systems inherit CompactPCI's innate higher availability characteristics. CompactPCI's hot-swap feature and front serviceable card cage minimize mean-time-to-repair (MTTR) by allowing maintenance personnel to easily remove and insert cards without taking down the system. Some CompactPCI systems on the market also feature hot-swappable fan trays, hard disk drives, and redundant N+1 power supplies to further increase uptime. Some have even been built to meet stringent Bellcore NEBS Level 3 criteria in order to support critical telephony applications that must keep functioning in the face of earthquakes, fire, lightning, power faults, and other natural disasters.

CONCLUSION
The robustness and high availability that CompactPCI brings to open systems solutions makes it an easy choice for deploying Internet telephony applications. Not only does it provide reliability characteristics that are in line with proprietary solutions, but it also places Internet telephony implementations on the PC price curve. Implementations gain from increasingly lower-cost, higher-performance silicon and widely supported operating systems. Off-the-shelf boards are available for a wide range of applications, and major vendors are introducing new boards with new functionality at a steady rate. Off-the-shelf software is also readily available. And custom application software can be developed on desktop PCs using popular programming tools, and then run without modification on CompactPCI systems.

Change comes quickly in the Internet telephony arena. Open systems are much better geared for both evolutionary and revolutionary change than are proprietary solutions. Plus, they integrate better with other open enterprise systems. Until recently, the open system challenge to proprietary systems in the Internet telephony space has been carried by traditional PCs. Now, by extending the cost-effective, flexible PCI bus architecture for critical applications, CompactPCI presents proprietary Internet telephony solutions with a genuine challenge that they will find increasingly difficult to counter.

Pocheng Shyu is a product line manager at Force Computers. Force, a Solectron subsidiary, is a leading designer and supplier of open, scalable system and board level computer platforms for the embedded market. A processor independent company, Force delivers products based on SPARC, Pentium, and PowerPC technologies. Force has been a leading supplier of CompactPCI products since 1996, and is also the second largest supplier of VME computing platforms. For additional information, visit the Force Web site at www.forcecomputers.com.







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