Plug pulled on comms interconnect

San Jose, Calif. -- Intel Corp. might have handily established its X86 processors and PCI Express interconnect as dominant computing technologies, but the world's biggest chip maker is taking a clobbering in the communications sector, where its Advanced Switching Interconnect (ASI) is in full retreat.

Intel and a handful of other chip makers have quietly pulled the plug on plans to build products with Advanced Switching, a variation of PCI Express for communications and embedded systems. ASI was supposed to pave the way for Intel to win fresh sockets in routers, switches, storage gear and other systems where the PC chip giant today plays a lesser role.

For the foreseeable future, only StarGen Inc. (Marlborough, Mass.) is shipping ASI silicon, and the startup will require another round of venture funding to meet its expenses through 2007. But a StarGen executive said the company has eight design wins and believes ASI could see a revival when second-generation chips hit in 2008.

Meanwhile, the PCI Special Interest Group is building extensions into Express that could take on some functions of ASI, even as Express surges forward as a native interface on computing and embedded processors. In other words, while Intel has lost a strategic round, expect it to bounce back.

How ASI failed
Intel proposed the PCI Express concept in December 2000 as a way to bring a technology that was software-compatible with the parallel PCI bus into the world of serial, gigahertz interconnects. Unlike PCI, Express was supposed to consider the needs of communications and embedded systems from the start, with a set of extensions tailored to their needs. Those extensions soon grew to a complete rewrite of the PCI Express transaction layer and were spun off as the Advanced Switching initiative, with its own Special Interest Group.

The ASI SIG finished the spec in early 2004. At that time, Eric Mentzer, chief technology officer of Intel's communications group, promised that Intel would produce network and I/O processors with native ASI interfaces. As many as 60 companies, including comms OEMs Siemens and Huawei, joined the SIG.

But comms OEMs were more accustomed to SPI, CSIX and Xaui than to PCI and Express. As engineers began crafting ASI silicon, it became clear that the big OEMs were less than fully engaged.

"They didn't have any firm plans to adopt the technology. If they did, they could have created a halo effect that would have given us momentum," said Kelly Ambriz, a marketing manager for Vitesse Semiconductor Corp., one of the founding companies on the ASI SIG board.

By late 2004, Intel began removing all mention of native ASI interfaces from its confidential product road maps. "We were in development with a switch that would have hooked up to one of those processors, so that was a big blow," said one silicon partner, who asked not to be identified.

Intel shifted its plans from creating silicon to enabling platforms and began to funnel more resources into the ASI SIG. It didn't take long for word about the OEMs and Intel to trickle down to chip makers such as Integrated Device Technology, Vitesse and others.

"In April 2005, I was asked to reevaluate our plans for an Express-to-ASI endpoint, and we wound up killing it," said the silicon partner. "At one point, we had half a dozen engineers dedicated to ASI SIG working groups."

A technical debate over the direction for ASI firmware further splintered partnerships. Today, IDT, PLX Technology, Vitesse, Denali and NEC all say they have no plans for ASI products. The technology became "overengineered--it niched itself," said Jeff Lukanc, a director of design engineering at IDT.

Some are unsure whether ASI will disappear or just go dormant. "We wrote off Infiniband, then it came back," noted Jack Regula, chief technology officer at PLX.

Vitesse's Ambriz said it "seems like ASI is pretty much dead."

Hammering another nail in the coffin, Intel is now expected to sell off its wired-communications business. That word comes on the heels of Intel's announcement in June that it was selling its wireless-comms unit to Marvell Technology Group Ltd. for $600 million.

But Wesley Shao, a senior staff engineer at Sun Microsystems Inc., said ASI technology fills a role not only for embedded systems but for computer servers as well. The ASI SIG recently kicked off a technical working group to simplify the protocol and reduce the footprint of ASICs for the interconnect, he added.

Keeper of the flame
Wade Appelman, vice president of marketing for StarGen, is quick to admit his company will be the only one producing ASI silicon for the foreseeable future. "The ecosystem has not evolved as we would have thought three years ago," he said.

Comms OEMs may not be adopting ASI, Appelman said, but some server and storage OEMs are. In addition, the rise of Express as a native processor interface and plans to push Express to 5 Gbits/second could give ASI a new lease on life, he said.

Although StarGen says it has eight design wins for ASI, it's unclear when those designs will enter volume production. Four of the design wins are with companies making single-board computers that typically ship no more than a few thousand units a year at best. Another is for an "application-specific server blade" that monitors quality-of-service parameters for 3G wireless networks and is housed in an Advanced TCA chassis, Appelman said.

One win is with Xyratex Ltd. (Havant, U.K.), an IBM spinout that makes hard-disk testers and storage gear. It has demonstrated a system that lets servers connect to a remote I/O box via ASI for automatic failover. The system will sample in August but won't hit volume until early 2007.

Later this year, Xyratex will evaluate plans for a follow-on product. Gary Lee, a business development manager for Xyratex, said "it's a concern" that StarGen is the only silicon supplier for ASI, but added that no other switch-chip companies have products that could replace what StarGen offers.

Meanwhile, both IBM Corp. and graphics chip designer Nvidia Corp. recently joined the ASI SIG. IBM said it joined because some customers asked its ASIC group for ASI cores.

StarGen's Appelman is betting on 2008 as ASI's breakout year, partly because that's when the 5-Gbit/s version of Express is expected to be widely available. That version will enable common four-lane backplanes to use Express to hit their 10-Gbit-plus targets. Today's backplanes can typically only get up to about 8 Gbits with the current, 2.5-Gbit Express.

Express will also be available as a native interface on a much broader array of processors and peripheral chips by 2008. Sun, for one, will put an Express interface on Niagara2, its next-generation multicore Sparc CPU.

"We are in a big way starting to implement PCI Express on a lot of products. It's replacing HyperTransport," designed by Intel archrival Advanced Micro Devices, said Doug White, a technology leader in high-speed design in the router group at Cisco Systems Inc. "Everyone I've talked to said Express is becoming more and more prevalent in our designs, but no one I know of is working on anything with ASI."

Express is being used for chip-to-chip links because it is appearing on an increasing number of merchant comms chips, he added. Cisco's router group uses proprietary interfaces on its backplanes, so is not considering Express there.

Express ranked as the third most familiar interface and the second most likely to see increased use in an EE Times Web survey of 243 engineers conducted in the spring of 2005. At that time, 82.2 percent of respondents said they were very or somewhat familiar with Express, and 63.9 percent said they were likely to increase their use of it over two years (search www.eetimes.com for article ID: 160502125).

Express vs. RapidIO
An all-out mind-share battle is being waged in the communications sector between Express and the competing Serial RapidIO interconnect developed by Freescale Semiconductor Inc. Unlike ASI, RapidIO (RIO) is gaining traction as an interface for PowerPCs and digital signal processors, especially as a way to link the farms of DSPs found in wireless basestations.

Unlike the ASI SIG, the RapidIO Trade Association has forged strong ties with tier-one OEMs. Last fall, representatives from Lucent Technologies, Ericsson and storage giant EMC Corp. were elected as association officers. One source close to Lucent suggested the company has a commitment to RIO and is not likely to use ASI.

But rising adoption of Express could shift that tide. Ambriz of Vitesse said he is recommending that people put native Express interfaces on their comms chips.

"You need to consider how many DSPs will add Express in the future," said StarGen's Appelman. "Once that happens, Serial RapidIO may not have the same advantages."

Indeed, even companies with a strategic stake in RapidIO are adopting Express interfaces--sometimes before RIO.

Applied Micro Circuits Corp. (Sunnyvale, Calif.) sells a PowerPC 440SPE processor that sports three Express interfaces and is geared for storage systems. It will announce its first CPUs with serial RapidIO before the end of the year, and also plans more devices using Express. "We are doing Express, Ethernet and Serial RapidIO. These are the three interfaces for our processors going forward," said Sam Fuller, vice president of marketing at AMCC.

Freescale ships a half dozen PowerPCs and one DSP using Serial RapidIO. Texas Instruments has two high-end DSPs using Serial RIO but also plans to start putting Express interfaces on future DSPs.

If ASI does not gain traction, some engineers may use the evolving extensions to Express to handle some of the capabilities of ASI. For instance, the PCI SIG is developing an I/O virtualization capability for Express that will allow multiple host servers to address multiple I/O subsystems, a capability StarGen's ASI silicon will support by 2008.

The virtualization work, however, does not support as large a fabric as ASI can handle. It also lacks some of the robustness features of ASI, said Michael Krause, who co-chairs the PSI SIG work group on I/O virtualization.

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