FRANKFURT, GERMANY, November 18, 2004 - Cogent Communications Group, Inc. (AMEX: COI), a multinational Tier One, optical Internet service provider, announced today that it is providing service at Interxion colocation facilities, a leading pan-European provider of collocation and managed services. The arrangement provides that Cogent's ultra fast, highly reliable Internet Protocol (IP) and Internet access services are immediately available in 6 Interxion Data Centers located in Germany, France, Belgium, Austria and Spain.

Cogent currently has a presence in over 85 markets throughout Europe and the United States, and the ISP operates over 25 of its own On-Net data centers. Colocation in Interxion's facilities affords Cogent entrée into several strategic facilities where important carrier class prospects are located.

With the Interxion deal, carrier and enterprise customers gain even more avenues to conveniently access Cogent's multiple OC-192 (STM-64) network backbone and choose from a variety of products including Layer 3, ring protected transit service and Layers 1 and 2 transport services with available interfaces ranging from a T1 to multiple wavelengths. Cogent's data center customers, whether they meet Cogent's Tier One network at an On-Net facility or at a carrier-neutral data center, are typically connected in 17 days or less.

"Since founding Cogent in 1999, we've worked diligently to assure our longevity, price competitiveness and unmatched quality in the global Internet market," noted Cogent CEO Dave Schaeffer. "The Interxion relationship is another example of how we continually strive to meet demand for reliable and cost-effective IP services -- in this instance by making our services available in state-of-the-art, secure colocation centers."

"With the presence of Cogent in our data centers, our customers will get state-of-the-art telecom and IP services as well as access to one of the largest networks in the world," said Anthony Foy, Interxion Group Managing Director.

Cogent's end-to-end optical network consists of multiple metropolitan IP-over-WDM fiber rings located in Cogent's major markets throughout Europe and North America. With a currently implemented capacity of 50 Gbps in Europe and 80 Gbps in the United States, Cogent's multi-national IP network is among the largest in the world and is scalable to a total capacity of over one Terabit. For more information about Cogent's products available in Data Centers throughout Europe, visit www.cogentco.com/eu.

About Interxion

Interxion is Europe's leading provider of carrier-neutral data centres and managed services. With 20 data centres across Europe, it has the largest footprint by far over and above its nearest competitors and currently supports 700 customers including enterprises, systems integrators, Internet service providers, content providers, mobile services providers, hosting and telecommunications companies. Since its foundation, Interxion has raised more than 300 Million Euros from a leading group of investors around the world, including Baker Capital, Residex, Bear Stearns, BNP Paribas, Goldman Sachs, CSFB and Morgan Stanley. For more information visit www.interxion.com.

About Cogent Communications

Cogent is a facilities-based provider of low-cost, high-speed Internet access and Internet Protocol, or IP, connectivity in North America and Europe. Cogent Communications' global headquarters is located at 1015 31st Street, NW, Washington, D.C. 20007.

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Information in this release may involve expectations, beliefs, plans, intentions or strategies regarding the future. These forward-looking statements involve risks and uncertainties. All forward-looking statements included in this release are based upon information available to Cogent Communications Group, Inc. as of the date of the release, and we assume no obligation to update any such forward-looking statement. The statements in this release are not guarantees of future performance and actual results could differ materially from our current expectations. Numerous factors could cause or contribute to such differences. Some of the factors and risks associated with our business are discussed in Cogent's registration statements filed with the Securities and Exchange Commission and in its other reports filed from time to time with the SEC.

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