CIENA Helps THUS plc Deliver First Carrier-Quality Gigabit Ethernet Service to UK 'National Network' Enterprise Customers.

Business Editors/High-Tech Writers

LINTHICUM, Md.--(BUSINESS WIRE)--Feb. 6, 2003

Leading UK Service Provider Awards Contract to CIENA for ONLINE Edge

Deployment

CIENA(R) Corporation (NASDAQ:CIEN), a leading provider of intelligent optical networking systems and software, today announced that THUS plc has selected CIENA's ONLINE Edge(TM) Multiservice Coarse Wavelength Division Multiplexing (CWDM) Platform to support its Local Area Network (LAN) extension services, known as "City Ethernet."

The deal allows THUS to offer true carrier-class, metropolitan and national Ethernet services at gigabit speeds to the enterprise market. Enterprise customers of THUS, one of the United Kingdom's leading providers of voice, data, Internet and call center services, are now able to use either "National Ethernet" or "City Ethernet" products to reduce data communication costs and remove geographical barriers, to achieve greater flexibility and agility within their businesses.

"City Ethernet" is a high-speed metropolitan Ethernet service that allows enterprise customers to link sites through private Ethernet connections operating at the same high speed as their office network. "National Ethernet" is a high-speed national Ethernet offering that extends the benefits of "City Ethernet" to include flexible bandwidth and tariffs to meet all customer needs and budgets.

Ethernet already powers most company LANs. For the majority of these companies however, when this traffic enters the leased line Wide Area Network (WAN) to travel to another office, it can slow to less than 10 percent of the LAN speed.

CIENA's ONLINE Edge Platform takes advantage of CWDM technology to deliver low-cost, high-speed services including Gigabit Ethernet, Fibre Channel and SDH services, to overcome this bandwidth bottleneck.

"Through a rigorous selection process, we recognized the technology utilized by CIENA's ONLINE Edge Platform cost effectively delivers carrier-class, high-speed data services," said Phil Male, chief operating officer, THUS plc. "Comprehensive performance monitoring features will give us high visibility of service delivery levels. In our business, this is critical."

"We are pleased to be working alongside THUS to meet a key business objective of delivering cost effective, high-speed data services to the enterprise market," said Rafael de Ory, managing director, EMEA for CIENA.

CIENA's ONLINE Edge CWDM Platform delivers service transparency through intelligent CWDM optical technology combined with industry-leading service aggregation. The compact and modular ONLINE Edge Platform is designed for enterprises and service providers who want to offer high-bandwidth services over a single optical infrastructure.

ABOUT THUS

THUS plc provides communications solutions to business customers throughout the UK under the THUS and Demon brands. In an industry punctuated by inexperience THUS can draw upon a knowledge base established over more than a decade in the delivery of data, telecoms and Internet services.

THUS delivers both standard and bespoke solutions to address customers' existing business needs and works hand in hand with customers to develop new business opportunities. The Company's record in the creation of innovative new services is complimented by an award winning focus on quality and full accreditation under the ISO9001 standard.

THUS is listed on the London Stock Exchange. For further information visit www.thus.net and www.demon.net

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 operating costs. Additional information about CIENA can be found at http://www.ciena.com.

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 CIENA's relationship with THUS, 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-K filed with the Securities and Exchange Commission on December 12, 2002. 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.