September 2002

Standard Response

BY JIM MACHI

What will they buy? They�ll buy products that can both consume and distribute these increased data flows. The products will require, among other things, faster and more capable silicon, increased I/O throughput, better cooling, increased availability, and faster internal routing. Since central office space is finite, these systems will have to be �bigger� without actually being bigger. That is, the systems will need to step up and handle the new requirements, at the same time conforming to some of the old ones.

Can current systems handle these new requirements? In the short run, yes. But the industry also sees that in the not-so-distant future, today�s open, modular system hardware architectures will be limited, specifically if the target environment is a central office (CO).

I think it�s appropriate to confine our discussion to future capabilities of open, modular systems. As we discussed in last month�s column, I believe we can attribute much of the incredible innovation in the Internet telephony industry � innovation we�d all like to see continue � to the use of open systems. With this in mind, the next leg of innovation for our industry is to bring these open, modular components to the CO using a standard hardware shelf targeted to meet expanding density and I/O needs.

Are we in good shape to continue using open systems as requirements become more demanding? Yes, and there is much progress in this area. One such initiative, called the Advanced Telecom Computing Architecture (ATCA), is being developed by the PCI Industrial Computer Manufacturer�s Group (PCIMG), the same group that brought us the CompactPCI* standard. ATCA has been designed from the outset to meet next-generation communication requirements, with the Version 1.0 specification release targeted for October 2002.

Let�s take a sneak peek at some of the features and benefits of ATCA.

Since we�re assuming these systems will have denser and faster silicon components, there will inevitably be more heat to dissipate. How does ATCA address this? First, there is a higher pitch between boards, which allows both increased airflow and the use of on-board heat sinks.

What about increased density? Again, we�ll assume new silicon will handle increased throughput. But with ATCA, board size also increases, allowing for more components on the board. While this may seem backwards, it also allows for better cooling, since there is a larger surface area over which the cooling air can flow. Since there will be more, denser, faster, and hotter components, the folks developing ATCA also believe the systems must be able to handle up to 200W in a single slot (as opposed to less than 70W in CompactPCI). In other words, the cooling had better be better.

What about increased availability and reliability? The power distribution scheme defined in ATCA is �48VDC (redundant feeds) to accommodate central office standards and central office battery backup. Also, as boards have more varied silicon, each with different voltage and current requirements, it becomes more difficult to supply each voltage required over the backplane. Therefore, if the standard hardware shelf can distribute a single higher voltage, locally converting it board by board, voltage distribution becomes easier. Granted, a per-board converter takes more real estate. But it also improves reliability by simplifying power supplies.

What about increased I/O throughput and faster internal routing, both crucial for keeping down latency as traffic increases? While the proposed ATCA 3.0 specification defines the mechanicals, power, and system management we discussed, it also defines a generic backplane capable of supporting a variety of switch fabrics with up to 5 Gbps signaling. The proposed 3.1, 3.2, and 3.3 specs detail different kinds of fabric support that can be installed into 3.0 backplanes. The 3.1 spec details the Ethernet fabric interconnects, similar to CompactPCI 2.16 but going beyond 1GbE. The 3.2 spec details InfiniBand* fabric interconnects. The 3.3 spec details StarFabric* interconnects. These fabric definitions ensure compatibility between the installed switch fabrics and processing boards that make up an ATCA system. With these different kinds of fabric support, you don�t need a bus arbiter active at all times, which allows for increased throughput.

So how does this relate to Internet telephony? As an example, let�s look at the ability to create high-density VoIP gateways. ATCA would provide the space and cooling to deliver the processing power to drive the large DSP loads necessary for transcoding. With today�s DSP technology, you could create gateway boards with densities of up to 8,000 ports.

There is one issue: There is no equivalent H.110 bus. But does this matter? With such large board densities, there may be no need to move the data off the board, right? Although that last comment was facetious, it is possible, depending on the design. Even so, buses are not well suited for the reliability and large port densities envisioned for ATCA. With ATCA, the system designer has a very high-speed packet interface that is fully capable of delivering voice over packet (VOP) and can scale well beyond the H.110 limitation as market conditions dictate. With a fabric backplane, the system designer uses TDM in a different way. It moves from being propagated within a system on a bus to being terminated on a card and carried over the serial fabric. This addresses the performance, cost, and scalability issues inherent with the H.110 bus.

If you like CompactPCI even a little bit, you�ll love ATCA. If you�re on a proprietary hardware architecture but don�t really want to be, you�ll love ATCA. And if you�re a developer looking to continue innovating, you�ll love ATCA. Best of all, if you�re a service provider looking for innovative and cost-effective solutions that meet your ever-increasing needs, you�ll LOVE the companies that sell you ATCA solutions.

Jim Machi is director, Product Management for the Network Processing Division of the Intel Communications Group. Intel, the world�s largest chip maker, is also a leading manufacturer of computer, networking, and communications products. For more information, visit www.intel.com.

*Other names and brands may be claimed as the property of others.

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