Concentric Selects Larscom's Broadband Access Products for Its Recently Introduced 'ConcentricIMUX' T3/FT3 Service.

MILPITAS, Calif.--(BUSINESS WIRE)--Oct. 5, 1999--

Larscom's Inverse Multiplexing Technology Enables Concentric

to Meet Growing Customer Bandwidth Demand

Larscom Incorporated (Nasdaq:LARS) today announced that Concentric Network Corporation (Nasdaq:CNCX) has deployed Larscom's broadband products throughout its network as the basis of their recently introduced "ConcentricIMUX" T3/FT3 multi-megabit service.

Concentric, a leading nationwide Internet Service Provider, has installed Larscom's Orion 4000 broadband access multiplexers (with T3 Clear and IMUX modules), Access-T45 T3 DSUs, and Mega-T inverse multiplexers to support high-speed customer access and backbone links. The Larscom products allow Concentric to offer customers cost-effective broadband services at speeds ranging from 3 to 45 megabits per second -- significantly above the bandwidth available from T1 or DSL services.

Previously, clients who wanted access speeds higher than T1 had no option other than full T3 delivered to their premise, which is much more expensive than this new architecture. Using Concentric's Multi-megabit family of Access Services, Concentric clients are able to purchase broadband Internet connections services at incremental rates well below the T3 rate.

Concentric is leveraging two Larscom technologies to enable the ConcentricIMUX service. Inverse multiplexing, pioneered by Larscom and implemented in the Mega-T and Orion 4000 IMUX products, combines multiple T1 lines into a fractional T3 (FT3) clear channel. Concentric can adapt to customers' growing needs simply by adding T1s to the channel. For higher FT3 rates where inverse multiplexing T1s is not economical, Larscom's Access-T45 and Orion 4000 T3Clear products allow Concentric to provision fractional T3 access at any multiple of 3 Mbps all the way to the full 45 Mbps T3 bandwidth. Concentric is installing high-capacity Orion 4000 hubs in its "Super POPs," and deploying Mega-T and Access-T45 units at the customer sites.

Orion 4000 Fills the Gap Between T1 and T3

"We're finding that T1 dedicated solutions alone do not provide a comprehensive enough solution for many of our customers. With ConcentricIMUX, along with our now even more cost effective family of FullChannel and FlexChannel T3 products, we are able to offer any level of bandwidth that our customers require," said Alan Bavosa, product manager for Dedicated Access, Concentric Network. "The use of Larscom's network and customer premise equipment, in conjunction with that of Concentric's other strategic partners, allows us to aggregate multiple broadband solutions onto one platform."

Concentric Network Corporation provides complete, easy-to-use Internet business solutions for small- to medium-sized companies and customized Virtual Private Network and data center services for larger organizations. Concentric's portfolio of services for small- to medium-sized companies includes high-speed DSL access, Web hosting and e-commerce. For larger enterprises, the company offers dedicated Web hosting and data center services. Concentric is the first application infrastructure provider, offering a suite of infrastructure services that enable application service providers to deliver applications and Web-based services over the Internet or a VPN. Concentric's VPN solutions enable an organization to securely and reliably communicate with its offices, mobile sales force, business partners, vendors and customers. Concentric's services rely on a high-performance, ATM-based network that covers North America, and through various partnerships, reaches internationally. Concentric also operates state-of-the-art hosting centers at strategic locations across the U.S. All Concentric services are backed by 24 hour/7 days a week customer support, and many are backed by strong service level agreements.

Larscom Incorporated is a leading provider of high-speed wide area network (WAN) access equipment used by network service providers and large corporate enterprises. Larscom is headquartered in Milpitas, with an East Coast facility in Research Triangle Park, N.C. and sales offices throughout the U.S. and the U.K. For additional information, please visit the company's web site at www.larscom.com or phone [phone].