Enterasys is suing LAN switching rivals Extreme Networks and Foundry Networks for patent infringement.

The company has filed a lawsuit this week that claimed the two are infringing on six Enterasys patents involving virtual LAN (VLAN) and multi-protocol routing technologies, as well as "several other networking technologies".

Earlier this month, Enterasys announced plans to shut down operations in New Hampshire, where the firm’s former parent company Cabletron was founded in 1983. The company plans to move 200 employees from New Hampshire to its Massachussetts headquarters. In May, the company said it will cut 300 jobs, or around 30 percent of its workforce after revenue fell short of expectations in the first quarter of 2005.

Foundry and Extreme accounted for 2.9 percent and 2.7 percent of the $13.9 billion worldwide Ethernet switch market in 2004, while Enterasys’ share of the market was 1.6 percent.

In May, a lawsuit brought by Lucent against Extreme ended when a court sided with Extreme on four out of five disputed patents.