as Someone once said, let there be light. interesting piece, IMO, on SONET follows.
for the record, i hadn't heard of israeli-based novanet. anyone? bueller?
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Electronic Engineering Times
June 28, 1999, Issue: 1067
Section: Semiconductors
10-Gbit/s Sonet rates head for mainstream
Loring Wirbel
Atlanta - The enduring message from Supercomm and Cable '99 is that 10-Gbit/second Sonet rates, once seen as an exponential step beyond the 2.5-Gbit/s OC-48, are shifting toward volume pricing. The trend is evident in the price of mixed-signal semiconductors that implement the electronic interface as well as special optoelectronic components used for laser diodes and photodetectors.
The first steps toward silicon implementation of transceiver functions at 10 Gbits/s are being made by vendors like Giga North America Inc.
OC-48, meanwhile, is enjoying the commoditization in functionality that is allowing semiconductor vendors to mix physical-layer functionality with data-link-layer framing and payload envelope stuffing-an important task for special-purpose protocol stacks like packet-over-Sonet. Two market leaders in Sonet transceivers, Applied Microcircuits Corp. and Vitesse Semiconductor Inc., are playing lead roles on the integration front, while mixed-signal specialists in other communications worlds, such as Level One Communications Inc., are taking their first moves into Sonet processing.
The Sonet craze is odd in a way, because the synchronous optical network was designed as a time-division multiplexed service, and TDM is usually perceived as old-fashioned by packet-switching experts.
But Sonet has found favor as a ubiquitous fiber-based hierarchical transport service, made more cost-effective by layering wave-division multiplexing on top of native Sonet rates. As it becomes the common transport for both asynchronous transfer-mode (ATM) cells and Internet Protocol packets, Sonet becomes the common platform for all broadband communications.
Bill Woodruff, vice president of marketing at Giga North America, is certain his company can lay claim to being the first to offer high-integration 10-Gbit parts in bipolar silicon, but Giga does not hold any process prejudices. Its GD165 series, including the GD16544 receiver/clock-data recovery and demux part and GD16555 transmit mux, are bipolar silicon devices utilizing a high-performance on-chip voltage-controlled oscillator (VCO).
But Giga also employs gallium arsenide heterojunction bipolar transistor processes for functions closer to the light source in the GD199xx family. Recent introductions in that line include the GD19902 auto gain control amp, GD19903 modulator-driver and GD19906 transimpedance amp.
Woodruff said that the recent interest in implementing large-scale OC-192 networks stems not only from low-cost semiconductors but also from optoelectronics advances that help to drive the Sonet business.
Several vendors, like Cielo Corp., are lowering the cost of laser interfaces by using vertical-cavity, surface-emitting lasers. But lower-cost transceiver modules with special laser sources from such developers as Ortel Corp., Hitachi Semiconductor America and Discovery Semiconductor Inc. are also coming to the rescue. The reduced-cost modules are helping to ease design tasks for developers from the data-networking world who might be developing Sonet interfaces for the first time.
"The evaluation-board program has gained all kinds of attention," Woodruff said. "The optics remain tough for implementing a 10-Gbit system, and developers need all the help they can get."
Waiting game
High-integration 10-Gbit designs are yet to come at AMCC and Vitesse, with AMCC in particular waiting for results from its silicon-germanium licensing work with IBM to proceed on an OC-192 program. In the meantime, however, the company can apply the digital-processor designs developed at Cimaron Communications Inc., which AMCC acquired, to link to AMCC's own Sonet framer designs.
The first of those devices was announced at Supercomm -- the Nile S1202 for STS-12 ATM/Sonet mapping. The single-chip device maps tributaries within an STS-12 (OC-12) signal, terminating section, line and path, and provides mapping for both ATM or packet over Sonet. Broadband marketing manager Ken Prentiss said that bringing Cimaron's existing OC-12 products to market was only a flavor of what might be possible as the two design teams work on high-integration mixed-signal OC-48 products.
At Vitesse, the company's FiberStream forward-error-correction chips for Sonet systems, introduced in May, were followed up in early June by the V-Frame 2.5, or VSC9112, a dual-mode chip for OC-48 that can handle both packet over Sonet and ATM over Sonet. The 352-pin, $295 device performs all section, line and path overhead extraction and insertion and is designed to interface directly with the VSC9110 ATM framing device and the VSC9111 transport termination receiver.
A new player from Ra'anana, Israel, Novanet Semiconductor, is determined to implement 2.5-Gbit physical-layer Sonet devices in a digital CMOS process. To provide a Supercomm test case, Novanet brought a quad-port physical-layer device for OC-3 (155-Mbit) networks, the NOV2124, as well as a single-port device for OC-12 (622-Mbit) systems: the NOV2221. Both are intended to interface directly to fiber transceivers and perform all ATM-layer and packet-over-Sonet processing for concentration on STS-3c or STS-12c data streams.
In its initial entry into Sonet markets, Level One is taking a different approach. Instead of aiming at 2.5-Gbit speeds with CMOS, the company has developed a 155-Mbit transceiver that can handle fiber or coaxial cable using a single design. Level One sees its LXT6155 as a universal device for digital cross-connect or add-drop multiplexer systems, particularly those that want to carry a mix of packet-over-Sonet and ATM traffic. |
