Network equipment maker Cisco Systems won a key victory in a sprawling legal battle with rival Arista Networks on Thursday as the U.S. International Trade Commission ruled Arista infringed three of Cisco’s patents with its ethernet switches used in computer data centers and servers.
The trade commission upheld a finding of infringement by a U.S. trade judge in February. The ITC, which investigates complaints of violations of U.S. intellectual property, also recommended an import ban against Arista’s products that infringe the patents.
The ITC’s ruling must now be reviewed by the U.S. Trade Representative, who can approve or disapprove of the commission’s orders.
Get Data Sheet, Fortune’s technology newsletter.
Cisco’s (csco) patents relate to managing and securing communications networks. The company filed its trade complaint in December 2014, seeking a ban on Arista’s switches.
The trade action is merely one front in a fierce legal battle between Cisco and Arista, which was formed by former Cisco employees. Cisco has a second trade-related investigation pending before the ITC, and a judge is scheduled to release findings in that case in August.
The companies, both based in California, have also sued each other in federal court in San Jose. Companies frequently turn to the ITC to win an import ban and to district court to win damages.