Arista CEO Jayshree Ullal this week blasted back at her former boss in a sharply worded response to Cisco’s patent infringement suit against her company.

Ullal, who formerly spent 15 years as a Cisco employee and reported directly to Cisco CEO John Chambers, cast the patent dispute as a case of “pioneers vs. protectors” in a post on Arista’s company blog.

“Protectors defend old habits and remain strongly entrenched in following legacy technology trends,” Ullal wrote. “They are often in denial of new technologies and market disruptions until it’s too late.”

In two federal lawsuits filed late last week, Cisco accuses Arista of violating 14 patents and infringing copyrights on its user manuals, which Cisco claims Arista copied wholesale — grammatical errors and all.

“Arista took an unfair shortcut to compete with Cisco using Cisco’s own technologies, while avoiding investments in employees, money, and time that would have been needed to develop products based on new technologies,” read one of the Cisco complaints filed in the Northern District of California.

Arista board member Dan Scheinman, himself a former general counsel at Cisco, wrote in an Arista blog post that the new lawsuits are “an attempt by a legacy vendor that is falling behind in the marketplace to use the legal system to try and slow a competitor who is innovating and winning.”

Ironically, patent reform is a key policy concern for Cisco, as we’ve previously reported. In March, Cisco was itself hit by a patent infringement suit by a firm that had bought up old Nortel patents.

But unlike that “patent troll,” Cisco is actively using the patents it seeks to defend, and does not use litigation as a business model, says a Cisco executive who is not authorized to speak publicly on the pending litigation.

Asked if a settlement was under consideration, Arista responded in a statement that it has “not had an opportunity to evaluate the claims in detail.”

“I am disappointed at Cisco’s tactics,” Ullal said in a statement provided to SDNCentral.

“It’s not the Cisco I knew.”