Copper Battles Optics in Backplanes
Today Accelerant Networks Inc. announces its second product, AN5500, which can transmit a total of 31.25 Gbit/s of data over the copper traces that make up printed circuit boards (see Accelerant Intros Transceiver). Not only does it deliver more total bandwidth than existing solutions, the chip also increases the amount of data per individual copper trace. Accelerant has designed the chip to send 6.25 Gbit/s of data per channel, twice as much as existing products.
And speeds are going higher. Yesterday (April 22) Broadcom Corp. (Nasdaq: BRCM) announced a chip called BCM8102, which delivers a single serial 10-Gbit/s signal over a copper trace (see Broadcom Sends 10-Gig Over Copper). This chip was used to send and receive signals over 30 inches of FR-4 (a standard PCB material) in a private demonstration at the Optical Fiber Communication Conference and Exhibit (OFC) in Anaheim, Calif., last month, the company says.
Right now, many systems vendors are using -- or considering using -- parallel optical modules to connect their high-speed backplanes, because optics can travel farther at high speeds (see Parallel Optics Boosts Bandwidth). Will the new products from Accelerant and Broadcom make copper look more attractive again?
The verdict seems to be that for companies like Juniper Networks Inc. (Nasdaq: JNPR) and Pluris Inc., which are building massively-scaleable "terabit" routers, parallel optics may still be the best option (see Juniper Goes Terabit With the T640). But for smaller switches and routers, these new chips may allow vendors to stick with copper, which is cheaper, rather than force an upgrade to optics, says Jim Tavacoli, Accelerant's VP of marketing.
The drawback is that both products are unique, so systems vendors must use the same chip on both ends of the link. "This has been an issue with customers," says Tavacoli. But, he contends, when they realize what performance improvement they are getting, they are prepared to make the tradeoff.
"I firmly belive that as higher speeds are reached, interoperability will be impossible until standards are agreed to," he adds. There is no standard at present, but a group of twelve companies is aiming to form an industry consortium to promote the development of 6.25-Gbit/s links, he says. The consortium won't be announced for a few months yet.
— Pauline Rigby, Senior Editor, Light Reading