Juniper executives tried to reassure investors today that there's no specific reason the company is predicting a slow start to 2016. Rather, all the signs point to a difficult business environment, executives said, and Juniper wants to be braced for bad news.

"It really comes down to the fact that 2016 has started with a lot of market volatility, and we have to see how that plays out with all our customers," CEO Rami Rahim said during Juniper's earnings call, referring to the bear market that's dominated Wall Street since Jan. 1.

Statements like that met with suspicion from analysts, who continued prodding to see if any particular product or customer segment was faltering. Juniper executives insisted that they're just wary of the whole economic backdrop, which they believe will affect customer spending.

"Many of my peers around the world will start to tighten things" if macroeconomic conditions don't improve, CFO Robyn Denholm said.

Juniper's new forecast came along with today's fourth-quarter earnings report. It calls for first-quarter sales of $1.15 billion to $1.19 billion. That would be roughly 11 percent lower than the first quarter of 2015. Investors are disappointed because Juniper had previously predicted revenues would drop 7 to 10 percent.

In other words, Juniper thinks the economy warrants turning up the pessimism a notch.

Juniper's long-term goals — 3 to 6 percent sales growth per year, and 25 percent operating margins — remain intact, Rahim said.

Rahim, who was installed as CEO a little more than a year ago, stressed that he's pleased with the company's product development, which includes new products issued in 2015 that should contribute to revenues this year. (Multiple times during the call, he cited the QFX10000, Juniper's latest spine switch, as an example.)

Juniper, like many switch and router vendors, thinks it has huge opportunities in the growth of data centers and the hybrid cloud. That includes Contrail, the company's software-defined networking (SDN) play.

"The Contrail win rate that we are seeing — six additional wins in the Q4 timeframe alone — is really healthy," Rahim said.

Rahim also noted that the acquisition of BTI Systems, announced yesterday, plays into that data center world.

It appears BTI will become an element of Juniper's software-defined wide-area network (SD-WAN) strategy, but more generally, the acquisition continues the ongoing trend of converging packet and optical networking.

"We think there are certain market segments, data center interconnect in particular and metro, that are going to need to move to this architecture," he said. But he feels it's not something that will contribute significantly to 2016 revenues.

In addition to reporting earnings today, Juniper announced that Robyn Denholm will be stepping down after eight-and-a-half years as CFO. She'll stick around long enough to file the 10-K (an annual report submitted to the SEC), which usually happens in late February.

Denholm's replacement will be Ken Miller, who is Juniper's senior vice president of finance.