Cisco's General Counsel has a blog on the subject.
From another article:
Arista was founded by former Cisco employees, many of whom are named inventors on Cisco's networking patents. Among others, Arista's: 1) founders, 2) President and CEO, 3) Chief Development Officer, 4) Chief Technology Officer, 5) Senior Vice President for Customer Engineering, 6) Vice President of Business Alliances, 7) former Vice President for Global Operations and Marketing, 8) Vice President of Systems Engineering and Technology Marketing, 9) Vice President of Hardware Engineering, 10) Vice President of Software Engineering, and 11) Vice President of Manufacturing and Platform Engineering all were employed by Cisco prior to joining Arista. Moreover, four out of the seven members of Arista's Board of Directors were previously employed by Cisco.