CENIC upgraded a 460-mile segment of its California Research and Education Network (CalREN) to provide high-capacity service up to 400 Gbps between Los Angeles and Sunnyvale, including nodes in Santa Barbara, San Luis Obispo, and Soledad. CalREN serves K-20 students, educators, researchers, and individuals at other public-serving institutions, operating more than 8,000 miles of optical fiber to about 20 million users.

The new 460-mile route is part of an overall strategy to upgrade CalREN to 400G. In 2019, CENIC upgraded the southern path of its network between Los Angeles and Riverside, including nodes in Tustin, Oceanside, San Diego, Escondido and Sun City (see "CENIC links Los Angeles and Riverside via 400G superchannel"). Work will start in the fall on upgrades to the final inland path, completing the network ring from Sunnyvale back to Los Angeles with nodes in Oakland, Sacramento, Fergus, Fresno, and Bakersfield.

Enhancing the latest coastal route to 400 Gbps required CENIC to upgrade the existing backbone network from fixed-grid technology to flex-grid spectrum reconfigurable optical add-drop multiplexers. Flex grid optimizes the amount of spectrum used per wavelength to allow more data capacity provisioned across fiber spans.

“We no longer have to be restricted to fixed-grid implementations,” says Sana Bellamine, senior optical engineer at CENIC. “This new method maximizes the capacity over the fiber, and it enables us to deploy next-generation transponders that can deliver high-capacity services at a lower price per bit.”

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