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Feature Article
August 2002

PICMG 2.16 Gains Critical Mass


It has become clear over the past several years that existing bus-based architectures for embedded design have been pushed to the utmost of their abilities. As a result, a flurry of new switching and interconnect architectures have emerged for standardization.

While used in varying forms over the years, the concept of standardizing a packet switching backplane architecture took shape with the ratification of the Ethernet-based PCI Industrial Computer Manufacturers Group (PICMG) 2.16 specification in September of 2001. Since then, PICMG 2.16 has gained considerable critical mass, with over 30 vendors providing a full range of 2.16-compatible products and numerous equipment manufacturers adopting PICMG 2.16 for next-generation system designs.

The PICMG 2.16 CompactPCI/Packet Switching Backplane standard leverages the ubiquity of Ethernet to bring a variety of benefits to equipment manufacturers and, ultimately, carriers and service providers worldwide. Additionally, several driving forces have pushed, and will continue to push, the use of Megabit and Gigabit speed Ethernet as a bus connectivity architecture.

Ethernet is everywhere, primarily because of its ease of use, global familiarity, and ongoing ability to continually evolve technically. Since its standardization by the IEEE in 1983, Ethernet has become the world�s most widely used LAN access method. At some point, 95 percent of the world�s data travels on Ethernet, and 85 percent of the world�s installed networks are Ethernet-based. As a result, Ethernet has become dominant in enterprise LAN networks and has caused the world�s most complex network, the public switched telephone network (PSTN), to begin a migration from a circuit switching to a packet switching methodology. Overall, this momentum is pushing Ethernet/IP to become the networking standard of choice, not only in LAN and telecommunications networks, but also in data communications, metropolitan area networks (MAN), wireless networks, home networks, and factory floor networks.

Currently, 100Mb Ethernet is representative of a �standard� LAN connection port, and, according to market research analyst firm Venture Development Corporation, the worldwide installed base of Gigabit Ethernet ports is expected to increase more than fivefold by 2004. Additionally, the 10G Ethernet standard, including transmission over SONET (Synchronous Optical Network) cabling, is nearing completion, targeted mainly as a carrier technology for metropolitan-area service providers, backbone aggregation of Gigabit links, or switch-to-switch connectivity.
Recently, Ethernet has made another important leap � into the backplane as a bus connectivity architecture within standards-based industrial computers.

Telecommunications infrastructure compute nodes, such as call processing servers, multimedia gateways, integrated access devices, or wireless infrastructure equipment, are based on either proprietary hardware architectures or standards-based architectures. Depending on the core competencies of a given equipment manufacturer (i.e., competencies in hardware versus software) one of the two architectures is chosen. Regardless of architecture, a backplane bus is involved to connect all internal elements of a compute node to allow communications and control by a CPU. The most popular and widely used backplane bus architecture in standards-based equipment is the Peripheral Component Interconnect (PCI). With CompactPCI, developers are given the best of both worlds with the commodity availability and pricing of PCI silicon and a ruggedized form factor.

The PICMG 2.16 architecture is changing the way systems are being designed by overlaying an Ethernet-based, packet switching architecture on top of CompactPCI to create an Embedded System Area Network (ESAN). Defined as a dual redundant star architecture, the PICMG 2.16 standard�s use of Ethernet provides node-to-node connectivity through redundant Gigabit Ethernet paths managed by high-performance Ethernet switch fabrics. In short, the chassis-based network resembles a typical Ethernet network found in most networking environments.

As demands on performance metrics, such as density, throughput, cost, and reliability continue to increase, moving system traffic from a shared-bus architecture such as PCI to an embedded Ethernet backplane such as PICMG 2.16 becomes necessary. Deployments of PICMG 2.16 systems are underway and can offer extended capabilities and performance an order of magnitude above current standards-based architectures.

PICMG 2.16 is ideal for most any application now based on the popular CompactPCI form factor but seeking much higher reliability, performance, and scalability. In fact, compliant first-generation switch fabrics already can deliver performance increases up to 40 times that of current PCI architectures � with more reliability and higher chassis density. And with an unprecedented number of vendors having collaborated on standardization of the spec and compliant products already filling the pipeline, there is a wide array of 2.16 products on which equipment manufacturers can build their next-generation systems.

Faster throughput rates and higher scalability may be enough to sell the advantages of 2.16 to the equipment developer, but what about the service provider? What does this �backplane� architecture mean to those looking to enter new markets and/or enhance or expand existing networks, all while adhering to their company�s return-on-investment model? And why is Gigabit Ethernet inside network equipment so important?

The PSTN is migrating to a packet-switched infrastructure. Overall, aspects of the telecommunications network are moving towards an Ethernet/IP model, including 10G Ethernet being used in the metro network and as a carrier technology, WI-FI networks being developed with the 802.11 standards, SS7 networks offloaded to shared IP networks, and storage networks.

Amidst this move towards Ethernet/IP, each piece of network equipment needs to keep relative pace with other segments to ensure the reduction of traffic bottlenecks. Since equipment based on PICMG 2.16 can perform at levels 40 times that of existing architectures, it is more capable of keeping pace in the overall network. And with the ongoing growth of Ethernet/IP-based networks and equipment, there exists the capability of providing a common networking scheme from end-to-end for any connection, whether it�s data, voice, or signaling. This commonality is where true performance and network interoperability advantages will take place.

While the chassis performance metrics for PICMG 2.16 equipment are attractive, operational advantages for the service provider can be equally attractive. For example, PICMG 2.16 allows for significantly higher slot density or capabilities capacity in a typical rack footprint. Higher slot density allows for more functionality to reside in the equipment and, in turn, a higher call volume in the same fixed physical space. Higher provisions for density translate into a greater return-on-investment on leased central office space, allowing the service provider to control costs by realizing a more efficient, more scalable call volume and a better management of lease expansions.

PICMG 2.16 systems also provide increased reparability on a per slot basis, without affecting other elements in the chassis. Similar to an enterprise network, it is not necessary to shut down the entire network to fix one element of the network. This all-important feature reduces mean time to repair (MTTR) specifications for network equipment through hot swappable blades and enables a higher degree of uptime.

Since PICMG 2.16 is a standards-based architecture, many of the silicon elements within the system are produced in higher volumes than those found in proprietary architectures. Therefore, the risks associated with single sourcing of equipment, or component obsolescence, are reduced dramatically.

Finally, because of the large number of equipment vendors who participated in the standardization of 2.16, less than nine months after its ratification over 30 vendors are already offering 2.16-compatible products. Many equipment manufacturers worldwide have either adopted 2.16 or are looking to adopt it in the near future. With this overwhelming acceptance by equipment vendors, service providers are beginning to find a wide variety of competitively priced, readily available 2.16-based systems to choose from.

PICMG 2.16 provides a viable Gigabit speed backplane architecture for equipment manufacturers. Using this architecture, service providers are offered true next-generation systems for 2.5G and 3G wireless infrastructure equipment, multimedia gateways and softswitch elements, signaling infrastructure equipment, call processing servers, integrated access devices, and more. Each application shares performance demand for capabilities such as high availability, density, reliability, and throughput, all which PICMG 2.16-based equipment is designed to address.

For the future, Ethernet in the backplane is already evolving from Gigabit speeds with a next-generation standard called PICMG 3.X, which is being defined with both Gigabit and 10G Ethernet speeds in mind. As Gigabit Ethernet proliferates as the common enterprise LAN connection, 10G Ethernet begins standard deployment as a carrier technology, and Ethernet/IP continues as the common communications mechanism, we will begin to realize overall network commonality with performance and deployment benefits coming to fruition.

Ed Bizari is director of marketing at Performance Technologies, Inc. PTI is a leading supplier of packet-based telecommunications and networking products for wireline, wireless, and next-generation Internet Protocol networks. The company provides carrier-grade technology solutions, including network access products, Ethernet switching products, and integrated SS7/IP solutions to network operators, equipment manufacturers and systems integrators worldwide. For more information visit the Web site at www.pt.com.

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