Hermes Europe Railtel Extends Contract With CIENA.

LINTHICUM, Md.--(BUSINESS WIRE)--February 17, 1999--CIENA Corporation (Nasdaq: CIEN) today announced that Hermes Europe Railtel (HER) has extended its existing relationship with CIENA as the supplier of dense wavelength division multiplexing (DWDM) optical networking products for GTS Carrier Services' (GTSG: Nasdaq and Easdaq) pan-European network build through April, 2000.

"CIENA's open systems approach to optical networking through DWDM is key to our ability to provision high-bandwidth services across our network and will be a critical element of our new IP service offering," said Jan Loeber, president, GTS Carrier Services and managing director, HER. "Partnering with a technology leader like CIENA will enable HER to handle the dynamic bandwidth and service demands of our carrier customers and the rapid Internet and data growth anticipated throughout Europe."

In a separate announcement last week, HER announced its intention to deploy Europe's first operational high capacity fiber optic Internet network carrying IP traffic directly over DWDM transport. The network, supported by CIENA's MultiWave Sentry 4000 and Cisco System's International routers, will potentially provide an increase in capacity of more than 10 times that of current operational IP networks and is expected to deliver dramatically lower operating costs.

This IP-over-DWDM platform will be deployed initially in six European countries. HER expects a controlled introduction to commence with selected customers in March. General service availability is expected for later this year.

"Aggressive, alternative carriers like Hermes Europe Railtel are driving true competition in the European Telcomm market," said Patrick Nettles, CIENA's president and chief executive officer. "By embracing the revolutionary vision of an IP-to-the-glass network, HER unlocks the bandwidth elasticity, service versatility and network scalability of optical networking -- all of which become critical differentiators to a competitive carrier. We're very pleased that HER has chosen to extend its existing relationship with CIENA." -0-

ABOUT CIENA Based in Linthicum, Maryland, CIENA Corporation is a market leader of open architecture, optical networking systems that form the core of telecommunications networks worldwide. CIENA's networking solutions utilize bandwidth expanding dense wavelength division multiplexing (DWDM) technology and include the MultiWave(R) 1600 long-haul transport system, WaveWatcher(R) network management software, the MultiWave Optical Add/Drop Multiplexer, the MultiWave Sentry(tm) enhanced long-distance transport system and the new MultiWave(R) Firefly and MultiWave Metro(tm) short-haul systems. Through its CIENA Services subsidiary, CIENA provides a range of engineering, furnishing and installation (EF&I) services for telecommunications service providers in the areas of transport, switching and wireless communications.

Additional information about CIENA can be found on its World Wide Website: http://www.ciena.com.

About GTS and Hermes Europe Railtel

Global TeleSystems Group is a leading independent owner and operator of telecommunications companies throughout Europe. GTS has five primary lines of business: GTS Carrier Services, which provides cross-border transport in Europe to other telecommunications companies; GTS Access Services, which provides facilities-based access services to businesses throughout Europe; GTS Business Services - Western Europe, which offers voice, data, Internet and other telecommunications services to businesses; GTS Business Services - Commonwealth of Independent States (CIS), where GTS is a leading alternative provider of high quality telecommunications services in Moscow, Kiev, St Petersburg and other cities in Russia and the CIS; and GTS Mobile Services - CIS, which operates cellular businesses in Russia and Ukraine.

GTS Carrier Services' HER network and its Internet transport facilities currently spans almost 10,000 kilometers across Europe, serving telecommunications carriers and Internet Services Providers (ISPs) in 20 cities. The network is expected to exceed 20,000 kilometers in 44 cities and 18 countries by the end of 1999 and 25,000 kilometers in 50 cities and 20 countries by the end of 2000. The network currently serves more than 50 carrier customers and more than 80 ISPs, representing virtually every major segment of the telecommunications industry.

NOTE TO INVESTORS:

Forward-looking statements in this release, 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, and 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 Annual Report on Form 10-K, as filed with the Securities and Exchange Commission on December 10, 1998