AT&T Deploys CIENA's MultiWave Metro Intelligent Optical Transport Systems.

Business Editors/Hi-Tech Writers

LINTHICUM, Md.--(BUSINESS WIRE)--May 22, 2001

CIENA Corporation (NASDAQ:CIEN), a global provider of intelligent optical networking systems and software, today announced that AT&T has successfully tested, certified and begun deployment of CIENA's MultiWave Metro(TM) intelligent optical transport system.

AT&T provides competitive local services to business customers in 71 major markets nationwide and plans to deploy CIENA's MultiWave Metro platform in a number of those networks to provide up to 24 wavelengths of protected OC-48 or OC-192 capacity per fiber. AT&T already is carrying "live" customer traffic using CIENA systems in its Los Angeles metro network.

"MultiWave Metro provides the capacity and flexibility needed to support the next generation of advanced communications services," said George Gawrys, transport network planning director for AT&T. "CIENA's expertise in optical networking technology will help ensure AT&T's continued delivery of cost-effective and reliable high-speed data services across our metropolitan area networks."

"As one of the world's leading providers of voice, Internet, data and video services, AT&T requires optimal network performance. We're pleased AT&T has selected CIENA to help build its metropolitan networks with intelligent solutions for greater speed, capacity and efficiency," said Gary Smith, president and chief executive officer for CIENA.

MultiWave Metro is a leading system for high-capacity (up to 10Gbps) optical service transport and protection in metropolitan networks. The Metro platform supports multiple topologies, protocols and protection arrangements on the same fiber pair and in the same network node.

Its open, standards-based architecture allows it to interface easily with all types of SONET/SDH, ATM and Fast IP equipment and is designed to be an ideal platform for providing ESCON, Fibre Channel, Gigabit Ethernet and rate-adaptive Gigabit Ethernet, FICON and digital video services.

ABOUT CIENA

CIENA Corporation's market-leading optical networking systems form the core for the new era of networks and services worldwide. CIENA's LightWorks(TM) architecture enables next-generation optical services and changes the fundamental economics of service-provider networks by simplifying the network and reducing the cost to operate it. Additional information about CIENA can be found at www.ciena.com.

ABOUT AT&T

AT&T (www.att.com) is among the world's premier voice, video, and data communications companies, serving consumers, businesses, and government. AT&T has annual revenues of nearly $66 billion and 162,000 employees, and provides services to customers worldwide.

Backed by the research and development capabilities of AT&T Labs, the company runs the world's largest, most sophisticated communications network, is the largest cable operator in the U.S., and has one of the largest, digital wireless networks in North America.

The company is a leading supplier of data and Internet services for businesses and offers outsourcing, consulting, and networking-integration to large businesses. Concert, the AT&T/BT Global Venture, serves the communications needs of multinational companies and international carriers worldwide.

In October 2000, AT&T announced a restructuring plan to create a family of four businesses, each operating under the AT&T brand, committed to uniform standards of quality. Under the plan, which is expected to be completed in 2002, each of these four businesses will become publicly held, trading as either a common stock or a tracking stock.

NOTE TO INVESTORS

This press release contains certain forward-looking statements based on current expectations, forecasts and assumptions of CIENA (the Company) that involve risks and uncertainties.

Forward-looking statements in this release, including, but not limited to, the use of CIENA's MultiWave Metro platform in a number of AT&T's networks to provide up to 24 wavelengths of protected OC-48 or OC-192 capacity per fiber, MultiWave Metro's ability to provide the capacity and flexibility needed to support the next generation of advanced communications services, the ability of CIENA's expertise in optical networking technology to help ensure AT&T's continued delivery of cost-effective and reliable high-speed data services across its metropolitan networks, the ability of the Metro platform to support multiple topologies, protocols and protection arrangements on the same fiber pair and in the same network node, the ability of Metro's open, standards-based architecture to allow it to interface easily with all types of SONET/SDH, ATM and Fast IP equipment and that Metro is designed to be an ideal platform for providing ESCON, Fibre Channel, Gigabit Ethernet and rate-adaptive Gigabit Ethernet, FICON and digital video services, and the cost savings, deployment timing and network management benefits of the Company's products, are based on information available to the Company as of the date hereof.

The Company's actual results could differ materially from those stated or implied in such forward-looking statements, due to risks and uncertainties associated with the Company's business, which include the risk factors disclosed in the Company's Report on Form 10-Q filed with the Securities and Exchange Commission on May 17, 2001.

Forward looking statements include statements regarding the Company's expectations, beliefs, intentions or strategies regarding the future and can be identified by forward looking words such as "anticipate," "believe," "could," "estimate," "expect," "intend," "may," "should," "will," and "would" or similar words.

The Company assumes no obligation to update the information included in this press release, whether as a result of new information, future events or otherwise.