SUNNYVALE, Calif.--(BUSINESS WIRE)--Juniper Networks (NYSE:JNPR), the industry leader in network innovation, today reported preliminary financial results for the three months ended June 30, 2015 and provided its outlook for the three months ending Sept. 30, 2015. Net revenues for the second quarter of 2015 were $1,222 million, a decrease of 1% year-over-year and an increase of 15% sequentially. Juniper’s operating margin for the second quarter of 2015 increased to 19.9% on a GAAP basis, a year-