3. Fortinet

Fortinet landed at the No. 3 spot on Q1's list of best-selling network security brands. The Sunnyvale, Calif.-based company sold 10,075 units in the quarter, down 22.5 percent over the same period last year. Fortinet also saw a drop in market share for units sold, from 13 percent to 10 percent. Fortinet said it has been seeing increased traction for its Security Fabric platform and messaging strategy, under which it brings together its broad set of security solutions, including its firewall appliances.