We are heading into an Ethernet and Express world. An analysis of the 243 responses to our Web survey indicates there is still some significant experimentation amid diverse new and old interconnect technologies, but these are largely second-tier options today and probably still will be tomorrow.
Overall, key embedded systems like wired and wireless communications and storage are moving most swiftly to adopt Ethernet and PCI Express as their main interconnects. They are stepping up experiments with newer interconnects like Advanced Switching (a derivative of Express for embedded systems) and RapidIO, but neither appears headed to the mainstream anytime soon. Meanwhile, work with HyperTransport and Infiniband is generally cooling down.
We culled out from our survey a group of 86 respondents we called pathfinders, because they said they expected to implement 10-Gbit interconnects in their systems over the next two years — indeed, almost half of them already have hit the 10-Gbit milestone. These pioneers validated the overall trend we saw toward Ethernet and Express.
In fact, our pathfinders were the strongest supporters of Express of any group in the survey, with 70.7 percent saying they expected increasing use of the technology over two years. Likewise, they were significantly above the average in plans for increasing use of Ethernet interfaces such as Xaui and 10Base-CX (at 36.3 and 44.3 percent, compared with 23.4 and 29.1).
Thank the computer industry, largely in the form of Intel Corp., for driving new interconnect standards such as Express and Serial ATA. In our survey, both ranked among the top 10 interconnects in terms of familiarity, current use and planned use.
The results are especially impressive when compared against the sometimes confusing backdrop of more than 20 different chip-to-chip and backplane-interconnect standards engineers must track today. The plethora of standards comes as systems builders are shifting from parallel to serial and from megabit to gigabit technologies.
While the monolithic computer industry has set its course, the Gigabit future is somewhat less clear for the more diverse communications, storage and embedded sectors. Respondents indicated Advanced Switching (AS), HyperTransport, Infiniband and RapidIO are all still contenders for new design wins; however, it is possible all these options will remain second-class alternatives to a mainstream move toward a combination of Ethernet in its many forms and Express.
RapidIO (RIO) and Infiniband were the most familiar to engineers in our survey, while AS trails significantly. However, AS closes the gap as a candidate for next-generation design wins where it is in a neck-and-neck race with RIO. Both of the relatively new candidates are surpassing the more established technologies of HyperTransport and Infiniband, which appear to be treading water in terms of future design wins.
Plenty to choose from
Our Web survey solicited opinions on 19 standard and proprietary interconnect technologies. When respondents were asked to share their biggest issues with interconnects, 16 said standards or interoperability issues were their prime concerns.
Nearly three-quarters of those surveyed said they agree that chip vendors are creating too many high-speed interconnect standards the engineers need to track. At least a quarter of respondents indicated they feel the need to pick winners and losers in the crowded field.
"There are many, many solutions out there fighting for mind share, and determining which will meet our goals and our customers' needs for reliability, implementability and cost-effectiveness is quite difficult," said one respondent. "The biggest challenge is obtaining unbiased information about the best technologies to pursue for high-speed interconnects," the respondent added.
Express on the fast track
What has become clear is that the computer industry has driven two of the newest technologies — PCI Express and Serial ATA — to the head of the class.
The serial PCI Express chip-to-chip link ranked third in our list of most familiar interconnect technologies, with 82.2 percent of respondents saying they were very or somewhat familiar with it. That put Express just behind the venerable PCI and Gigabit Ethernet (at 91.4 and 90.1 percent, respectively), and well ahead of Fibre Channel (at 74.5 percent), even though the latter technology has been available in the market for a decade.
For its part, the Serial ATA interface for hard-disk drives ranked seventh on our list, with 64.6 percent of respondents saying they were very or somewhat familiar with it. Only 5.8 percent said they were not familiar with SATA, and nearly a third (30.8 percent) said they have used the technology, which has only recently become available.
Express ranked fourth among the 19 technologies in terms of current use, with 40.4 percent of respondents saying they have used it. That's astounding, given that the technology has only been shipping in products for about one year, primarily in PC chip sets and associated silicon from Intel. The high score probably indicates a number of pending products that are just starting to emerge from the pipeline.
By contrast, just 18.8 percent of respondents said they have used HyperTransport, even though the parallel chip-to-chip link developed by Advanced Micro Devices Inc. has been available in a range of computer and communications products for several years. HyperTransport ranked ninth in terms of familiarity, with 55.6 percent of respondents saying they were very or somewhat familiar with it.
Respondents ranked Express and SATA Nos. 2 and 3 (with 63.9 and 43.2 percent, just behind Gigabit Ethernet) when asked which technologies they expect to increasingly use over the next two years. The 5-Gbit version of Express, for which the standard is just now being defined, ranked fourth at 42.1 percent.
Horse race in comms
In the race to become the interconnect for tomorrow's communications systems, respondents gave Infiniband a slight edge in familiarity with 57.4 percent, saying they were very or somewhat familiar with the technology. That put it ahead of HyperTransport and RapidIO by a slim margin and a notch above Advanced Switching, which trailed at 46.7 percent.
Infiniband also has a slight edge in current usage as the only comms-related interconnect to make it into the top 10 here, with 20.4 percent. Here again, HyperTransport and RIO trailed by a couple of points, while AS lagged at 11.7 percent.
But oh, how the tables turned when we asked respondents about their future-use plans. Suddenly Infiniband was dead last among the quartet with only 17 percent saying they will increasingly use the technology over the next two years while a similar portion said they will decrease their use.
By contrast, AS and RIO are in a statistical dead heat, with about 25 percent of respondents saying they will increasingly use these links and only 11.5 percent saying they will decrease their use of them. HyperTransport is treading water in the middle with about 20 percent planning to increase use and 16.4 percent planning the opposite.
The responses indicate that HyperTransport and Infiniband have failed to make hay with their advantage of being first to market. Relative newcomers AS and RIO are quickly grabbing mind share and design wins over these entrenched candidates, though no technology has yet emerged as a clear winner.
That said, AS still lacks visibility, with 26.4 percent of respondents saying they were not familiar with the technology. Ironically, HyperTransport, one of the first of those four technologies on the scene, is in a somewhat similar boat with 15.2 percent saying they were not familiar with it.
Success factors
We asked respondents to grade a handful of the technologies with which they said they were most familiar so we could get a better idea of the success factors for interconnects. Repeatedly, respondents indicated they favored standards that had an active consortium and multiple vendors backing it and technologies they perceived as being scalable and low in overhead.
Interestingly, AS was the only technology that respondents said did not have an active consortium, suggesting the AS Special Interest Group has kept too low a profile to date. By contrast, RIO ranked high for having a strong consortium, but low in terms of having multivendor support. That suggests OEMs need to hear more from RIO chip members about their plans.
An analysis across major market sectors reveals deeper insights about the strategies of OEMs and the resulting status and outlook for these interconnects.
For instance, Infiniband's greatest strength today is in the storage sector, where 32.3 percent of respondents said they use the technology. Only 12.3 percent of storage respondents said they plan to increase use of Infiniband over the next two years, however. Meanwhile, 33.3 percent of storage OEMs said they are decreasing use of Infiniband — compared with 17.5 percent for all respondents — ranking Infiniband second only to PCI as the most likely interconnect that storage OEMs will phase out.
The portion of storage OEMs that are cutting back on the use of RapidIO (23.2 percent) and AS (18.2 percent) also exceeded the average for our survey (at 11.5 percent for RIO and 11.4 percent for AS).
It turns out that both storage and comms OEMs say Ethernet and Express are becoming their mainstream interfaces. Everything else is slowing down or remaining a second-tier effort.
Storage OEMs said they will increase their use of Ethernet and Express at a significantly faster rate than the average respondent. For instance, 40 percent of storage OEMs said they plan to increase use of Xaui compared with 23.4 percent for the survey as a whole. Results were similar though less dramatic for 10GBase-CX4 and backplane Ethernet. It's worth noting, however, that storage OEMs also will increase work on AS faster than average (34.5 percent compared with 24.6 percent on average).
Leaning on Ethernet
Wired and wireless comms OEMs tell a similar story, although they leaned a little heavier on the Ethernet foot, with 70.5 percent ranking Gigabit Ethernet as their top interconnect for increasing use over the next two years. Rankings for use of Express, Xaui, -CX4 and backplane Ethernet were also higher than average.
While comms OEMs indicated increasing use of AS and RIO, that use is clearly at a second-tier level, below even such storage interconnects as SATA and Fibre Channel. That indicates comms OEMs may see the move into storage networking as more important than experiments with new interconnect technologies.
A mixed bag of embedded markets in consumer, industrial, medical and military provided few surprises. They are following the crowd in adopting Ethernet and Express. However, they are more prone to experiment with RIO (which is closely tied to the PowerPC and some DSPs) than to AS, which is linked to the Intel X86. In addition, these embedded OEMs will cling to the parallel PCI and PCI-X buses longer than the average respondent.
Our survey shows Infiniband will shift from storage to servers as its strongest market in the next two years. RapidIO will keep its current stronghold of adoption among non-comms embedded systems. And HyperTransport and Advanced Switching will both see servers as their strongest market. For AS, this indicates a lack of market education because servers are not a primary target for the technology.
One last conclusion: The transition away from parallel buses seems to be in full swing. PCI and PCI-X ranked at the top of interconnects users are migrating away from, with 36.4 and 23 percent respectively saying they expected to decreasingly use them over the next two years. HyperTransport, also a parallel bus, albeit with high speed and low latency, ranked fifth on that list at 16.4 percent.
Our pathfinders are stepping away from the parallel buses even faster, with 44.6 percent saying they expect to decrease use of PCI over two years and 23.1 percent saying they will decrease use of HyperTransport.
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