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Technology Stocks : Ciena (CIEN) -- Ignore unavailable to you. Want to Upgrade?

To: James Fulop who wrote (7816)	12/7/1999 2:39:00 AM
From: KENNETH DOAN	Respond to of 12623

Dec. 06, 1999 (FIBER OPTICS NEWS, Vol. 19, No. 47 via COMTEX) -- How far is far enough between nodes in a DWDM network? Ciena Corp. [CIEN] has just raised the bar. The Linthicum, Md., company has reconfigured its MultiWave CoreStream DWDM system to transmit signaling up to 5,000 km before another CoreStream terminal is required to boost signal strength. "If you look at traditional networks, they have a lot of POPs and break down service into DS-3s, and aggregate voice calls onto the DS-3s at the POPs," says Dave Evans, Ciena marketing director for transport products. "But in new carriers there is a data-centric approach. These carriers have a dozen nodes in their network to cover the entire United States. They have terabit routers in those POPs, and 1,500 to 2, 000 km between the POPs. We could interconnect the POPs with our new configuration for CoreStream. The distances could be further apart if you need to, up to 5,000 km. "The MultiWave CoreStream is a DWDM system that has C (or conventional) and L (or long-wave) bands. The C band operates between 1527 nm and 1565 nm while the L operates between 1566 nm and 1625 nm. Together, the bands can support up to 2 Tbps, or 200 OC-192 channels. The CoreStream offers 24 channels of 10 Gbps capacity in each 7- foot rack. The Secrets Of Long-Haul Configuration Ciena developed "Long-Haul Config-uration" for the CoreStream by using forward error correction and dispersion compensation. Forward error correction applies a coding algorithm to DWDM signaling that allows bit errors to be corrected. A computation is done before a signal is transmitted to discover the placement of bits in a signal. Then, overhead bits are added to a signal before it is transmitted. In the case of the CoreStream system, a signal becomes a 12- gigabit transmission instead of a 10-gigabit transmission, and two gigabits of the signal are out of band. In the extra bits lies performance-monitoring brethren. When a signal is received, the extra two gigabits are stripped, and a computation is done to see if any of the bits in the 10-gigabit signal are incorrect. If so, they are replaced. Forward error correction allows a DWDM signal to travel further by keeping it free of bit errors. The technique employs an application-specific integrated circuit, so it is imbedded in a module that can be plugged into the shelf of a CoreStream system. Dispersion is the property of light in which its wavelengths arrive at a destination at different speeds. It is compensated for in Ciena's amplifiers. Ciena has integrated dispersion compensating fiber into the amplifiers to make sure different wavelengths of light arrive at their destinations at the same time. Ciena has not released pricing for the new configuration of the CoreStream. "The fact that Ciena is doing something to reduce the number of repeaters is good," says Craig Johnson, principal of the PITA Group, a high-tech consultancy in Portland, Ore. "Carriers want this because they can save money. More importantly, if I put in a repeater and it fails, I'm in trouble. The cost is made up of potential down-time costs, and the mean time to repair."