Sycamore Networks Successfully Demonstrates Control Plane Interoperability in Worldwide Demo.

CHELMSFORD, Mass. -- Sycamore Networks, Inc. (NASDAQ: SCMR), a leader in optical networking, today announced the Company successfully demonstrated multi-vendor, multi-layer control plane interoperability using the Optical Internetworking Forum's (OIF) User-to-Network Interface (UNI) 2.0 and External Network-to-Network Interface (E-NNI) in a worldwide demonstration that featured dynamic Ethernet connectivity in a multi-carrier, multi-continent environment.

As part of the OIF Worldwide Interoperability Demonstration, Sycamore's intelligent optical switching equipment participated in several weeks of unified control plane testing hosted by industry-leading carriers on three continents, including Verizon and NTT Laboratories. In addition, Sycamore's involvement in this test event featured successful Ethernet-over-SONET/SDH demonstrations of E-LINE and E-LAN services using its Universal Service Card (USC), a modular service interface card for the SN 16000 intelligent optical switch.

During the multi-vendor test event Sycamore demonstrated dynamic service creation based on the OIF UNI 2.0 and E-NNI implementation agreements, which satisfy International Telecommunication Union-Telecommunication's (ITU-T) requirements for automatically switched optical networks. Sycamore's comprehensive Ethernet solutions support the ITU-T standards for the efficient transport of Ethernet traffic over a SONET/SDH infrastructure, including Virtual Concatenation (VCAT), Generic Framing Procedure (GFP), and Link Capacity Adjustment Scheme (LCAS).

"Sycamore's participation in this multi-carrier demonstration underscores our continued commitment to standards-based networking and reinforces our leadership position in intelligent control plane solutions," said Thomas DiMicelli, senior product marketing manager at Sycamore. "We continue to provide our customers with, what we believe to be, the most advanced means to efficiently and cost-effectively manage bandwidth in the optical network."

About OIF's Worldwide Interoperability Demonstration 2005

The Optical Internetworking Forum (OIF) is sponsoring the industry's second international joint carrier, multi-vendor optical networking interoperability demonstration. The event, conducted simultaneously in China, Japan, Germany, Italy, France and the United States will highlight network interoperable solutions among the participating vendors employing OIF implementation agreements in a multi-carrier environment. The global interoperability event will include testing of User Network Interface / UNI 2.0 Ethernet over multiple SONET / SDH transport networks interconnected by control plane External Network-Network-Interfaces / E-NNI.

An overview of the event will be on display June 7-9 at SUPERCOMM 2005 in Chicago, OIF Booth #50094. Additional information can be found at http://www.oiforum.com.

About Sycamore Networks

Sycamore Networks, Inc. (NASDAQ: SCMR) develops and markets optical networking products for telecommunications service providers worldwide. The Company's products enable service providers to easily and cost-effectively transition their existing fiber optic network into an infrastructure that can provision, manage and deliver economic, high-bandwidth services to their customers. For more information, please visit www.sycamorenet.com.

Note to Editors: Sycamore Networks, etc. are trademarks of Sycamore Networks, Inc. All other trademarks are the property of their respective owners.

Except for the historical information contained herein, we wish to caution you that certain matters discussed in this news release constitute forward-looking statements that involve risks and uncertainties. Actual results or events could differ materially from those stated or implied in forward-looking statements due to a number of factors, including but not limited to: the Company's ability to file its periodic report on Form 10-Q pending the completion of the currently ongoing Audit Committee internal investigation; unfavorable conditions in the telecommunications industry and economy in general; the pursuit of strategic and financial alternatives; the commercial success of the Company's line of optical networking products; the significant cost structure required to support the Company's strategy; competition; the Company's reliance on a limited number of customers; the Company's ability to sell through distribution channels; variation in the Company's quarterly results; manufacturing and sourcing risks; product performance; conducting business internationally; current and potential litigation; intellectual property rights and disputes; stock market volatility and capital market conditions; and the other factors discussed in the Company's most recently filed Form 10-Q and the other reports filed by the Company from time to time with the Securities and Exchange Commission. There can be no assurance that any transaction or other corporate action will result from the Company's review of strategic and financial alternatives. Further, there can be no assurance concerning the success, type, form, structure, nature, results, timing, or terms and conditions of any such potential transaction, even if such an action does result from this review. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future results or otherwise.