Cisco Systems forecast slower long-term revenue growth Thursday, citing conservative spending by its customers and uncertainty about the economy in some parts of the world. The company predicted overall revenue growth between 3 and 6 percent, stepping back from a long-term forecast of 5 to 7 percent that it made in 2011. The new forecast is for a compound annual growth rate over the next three to five years, according to slides from a presentation by Executive Vice President and Chief Financial Officer Frank Calderone at Cisco's annual financial analyst conference.