SAN FRANCISCO — On the witness stand Monday, Silicon Valley entrepreneur and investor David Cheriton described an amicable relationship between the two companies he founded back-to-back in 2004.

For the first several years, no one on either side complained about the licensing agreement that allowed Arista Networks Inc. to use OptumSoft Inc.'s software development platform, called TACC, royalty free. Nor was there fuss over the caveat that required Arista to give OptumSoft ownership of any improvements made to the platform.

“We were operating in a very friendly, gentlemanly way,” Cheriton told the court.