Cisco's hated rival Arista has won a big victory in court

Arista just won a big portion of its legal battle with arch-rival Cisco, but it's not over yet.

A San Jose, California, jury has ruled that Arista did not violate Cisco's copyright and did not infringe on Cisco's patents, reports the Wall Street Journal.

That means that Arista is not on the hook to pay Cisco the $335 million in damages Cisco was seeking, reports Forbes.

At issue was a part of Arista's software called the command line interface (CLI), where users type in commands. Cisco argued that Arista illegally copied Cisco's CLI. Arista argued that Cisco's CLI has become widely adopted by many products and Arista's use of it was fair.

Underlying this lawsuit is the fact that Arista is doing well selling its switches, to the detriment of the market leader, Cisco. It doesn't help that Arista also employs many former Cisco star employees, including Arista cofounder Andy Bechtolsheim and its CEO Jayshree Ullal.

While the civil suit may be a win for Arista, Cisco pulled out all the stops when it decided to sue Arista, including filing complaints with the US International Trade Commission.

Last week, the ITC ruled that Arista's products violated two of Cisco's patents. The ITC had also previously ruled that Arista products violated other patents and for a short while Arista products were banned from being imported into the US from their overseas manufacturing sites. Arista has since redesigned its products to remove the offending technology and ended the ban.

So there's still another round of legal hurdles with the ITC for Arista to jump through. But investors seem at least a little relieved by Wednesday's good news. The stock is up about 3%.