By Michael Calia 

Spherix Inc. on Thursday said that it is suing Cisco Inc., alleging that $43 billion in Cisco sales infringed on Spherix patents.

Spherix--which described itself as an "intellectual property development company committed to the fostering and monetization of intellectual property" -- said Cisco infringes on 11 patents it acquired in December.

The patents, Spherix said, were developed by inventors at Nortel Networks, which filed for bankruptcy protection in 2009 and subsequently sold off its patent portfolio and operations.

"The company believes that the vast majority of Cisco's switching and routing revenue from March 2008 through the present has been generated by products and services implementing technology that the company believes infringes on the 11 patents," Spherix said.

Cisco representatives didn't immediately respond to a request for comment.

Write to Michael Calia at michael.calia@wsj.com

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