Last week's Intel Developer Forum paid a lot of attention to PCI Express, the company's next-generation PCI technology. PCI Express is designed for PCs, but, like PCI, it will be used in plenty of non-PC applications as well. In the networking market, PCI Express will go head to head with HyperTransport and RapidIO.

PCI Express is already gaining traction in networking. A few months ago, we polled 3,500 readers of our NPU Wire e-newsletter on which standard they believe will prove most popular for chip-to-chip interconnect in networking applications. PCI Express received 79 percent of the votes, swamping HyperTransport, RapidIO and PCI-X.

Intel's strong backing is one key to the popularity of PCI Express. The standard will first appear in Intel's PC chip sets in next year's second half. Thanks to the PC platform's huge volumes-and to Intel's near-lock on the market-PCI Express shipments will likely exceed 50 million systems in 2006.

Such volumes will attract third parties to develop bridge chips and other supporting products. That infrastructure, in turn, will encourage use of PCI Express in networking and other non-PC applications. Intel, priming the pump, is committed to deploying PCI Express in its own network processors.

Ironically, competition for PCI Express in networking will come from another Intel standard, now known as Advanced Switching for PCI Express. Intel originally positioned the standard as a PCI Express version optimized for networking. In that view, PCI Express would be used in PCs and Advanced Switching in networking equipment.

Now that the Advanced Switching specification is nearing completion, however, it is clear that it will be incompatible with PCI Express at the protocol layer, though they share the same physical specs. As a result, Advanced Switching cannot leverage the economies of scale of the PCI Express infrastructure. Look for Intel to drop PCI Express from the Advanced Switching specification's full name to clarify that difference.

PCI Express will be widely used for simple chip-to-chip communication in networking gear, since it is inexpensive and adequate for that purpose. We see PCI Express, not Advanced Switching, becoming the most popular next-generation interconnect for networking chips.

Linley Gwennap is founder and principal analyst of The Linley Group (www.linleygroup.com).