'Wrap-A-Ho? Wazzat?'

Will the real successor of the PCI bus now step forward? Is it InfiniBand, or is it this new fangled thing called 3GIO, code-named Arapahoe?

At last weeks Intel Developer Forum -- a venue packed with InfiniBand promoters -- some people weren’t too sure. ”Wrap-a-Ho? What’s that about then?” asked one chip engineer cruising the show. “Arapahoe, yeah, nice mountain range. No, really, it’s the new data center interconnect, right?" said another attendee.

Wrong actually, although it’s easy to see why someone might get that impression. Intel Corp. (Nasdaq: INTC), the company behind both technologies, has kept people guessing over the likely applications of InfiniBand and Arapahoe, referring to both of them as “data center interconnects” and "PCI successors" at one time or another.

It would be to easy to conclude that they’re competing technologies when, in fact, they’re complementary.

InfiniBand may have started out as a next-generation PCI bus project, but it’s now being positioned as a replacement for Ethernet in the data center, although Intel won’t come right out and say this yet. (see InfiniBand Steals the Show). The InfiniBand Trade Association however, isn't so coy. It says the aim of InfiniBand is to connect servers and storage system together in the data center.3GIO (aka third-generation I/O, aka Arapahoe), on the other hand, serves a very different purpose. It provides a serial connection between the components inside the server and is supposedly much faster than PCI-X, the latest I/O interconnect, at doing this.

Speeding up the communication between the components on the board dovetails with InfiniBand, which speeds up communication between servers. “It means that the computing side of the data center should eventually keep up with the networking side, which is critical for storage networking, which is where the two come together,” says Dan Tanner, analyst with the Aberdeen Group.

“InfiniBand provides a box-to-box connection with shared I/O resources, but it can also provide slots inside boxes which is where the confusion comes in,” says Roger Tipley, chairman and president of the PCI-SIG (special interest group). “Intel realized it needed something more specific than InfiniBand for I/O and came up with Arapahoe.”

“PCI replacement is an old spin on InfiniBand," says Tipley. "Intel needs to drop this one now,” he adds.

PCI-SIG has been brought in by the so-called Arapahoe Work Group to help promote and support the proposed 3GIO standard -- repeating what it's already done for PCI (see Heavyweights Back PCI Successor). The Arapahoe Work Group originally comprised Intel, Compaq Computer Corp. (NYSE: CPQ), Dell Computer Corp. (Nasdaq: DELL), IBM Corp. (NYSE: IBM), and Microsoft Corp. (Nasdaq: MSFT). Last week, a further 22 vendors joined PCI Successor Gets Industry Backing).The PCI-SIG has its work cut out, though, as the punters aren’t the only ones who are confused. Intel’s 3GIO partners aren’t exactly crystal on the message either. “There are striking similarities between the InfiniBand and 3GIO,” says Margit Evensta, SCSI product manager at LSI Logic Corp. (NYSE: LSI), a company building SCSI controllers that connect to whatever PCI interface is on the other end. “Intel steals with pride from other interfaces, which makes things confusing,” she says.

The Arapahoe Work Group plans to hand over the 3GIO specification to the PCI-SIG in early 2002. Test equipment and tools will likely appear in late 2003, and the first desktop computers using 3GIO will begin to emerge in mid to late 2004.

Of course, true timelines depend on the market acceptance -- and on whether Intel comes up with yet another I/O architecture in the meantime.

— Jo Maitland, Senior Editor, Byte and Switch http://www.byteandswitch.com