PMC Targets Enterprise Ethernet

PMC-Sierra Inc. (Nasdaq: PMCS) is dipping further into the enterprise market, announcing a second enterprise-minded chip in its Xenon family of products.

The PM3393 S/UNI 1x10GE-XP, announced yesterday, resembles PMC's existing PHY chip for 10-Gigabit Ethernet but uses the four-lane XAUI interface, as opposed to the older 16-bit interfaces for 10-Gbit/s Sonet and Ethernet.

Small difference, but it's an indication that PMC is taking the enterprise market seriously. XAUI is a more compact interface, but each of its four lanes has to transmit at 3.125 Gbit/s, a speed high enough to be unreliable at long distances. So, XAUI comes in handy if you're trying to build a more compact (i.e., cheaper) system that's connecting across relatively short distances -- two criteria important for an enterprise box.

A pure 10-Gbit/s interface would be even nicer of course, but given that these are electronic links rather than optical, "that technology is nowhere near ready for prime time," says Steve Perna, vice president of PMC's service provider division.

PMC's interest in the enterprise isn't hard to figure out -- all of the major equipment providers are looking to the enterprise as a source of revenues in lean times. Enterprise-based Ethernet is a relatively new field for PMC, however, and the new S/UNI device gives some indication of the company's likely role in this market.

Specifically, PMC's new chip doesn't quite tread on the 10-Gig Ethernet turf being carved out by Broadcom Corp. (Nasdaq: BRCM) and Marvell Technology Group Ltd. (Nasdaq: MRVL), the companies whose chips rule the market for Gigabit Ethernet.

PMC is concentrating strictly on Layer 1 work. That is, the PM3393 is a physical-layer component for a Layer 2 ASIC built by companies such as Cisco Systems Inc. (Nasdaq: CSCO); and one of its primary functions is to translate between the XAUI interface of 10-Gigabit Ethernet and the SPI-4 Phase 2 interface used by most 10-Gbit/s network processors and ASICs.

This is a reflection of the kind of business PMC has focused on. "A lot of our customers like to be able to do their own Layer 2s," says Perna.

By contrast, Marvell's tendency has been to combine Layer 1 and Layer 2 parts into all-in-one switching chips such as its Prestera MX-630 (see Marvell Unveils Ethernet Switches). And Broadcom's main entry into the 10-Gig Ethernet realm is its BCM8701 transceiver (see Broadcom Offers 10-Gig Ether Bits), which lacks some of the pieces that PMC integrated into the PM3393 -- a media access controller, for example.

The S/UNI 1x10GE-XP is a follow-up to the Xenon set of chips released last year (see PMC-Sierra Touts Flexible 10-Gig Chip). The new chip is due to begin sampling later this quarter.

— Craig Matsumoto, Senior Editor, Light Reading

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