Starting what almost surely will be its first year with revenue of $1 billion, Arista Networks ( ANET ) connected with buyers, who drove the stock up by double-digit percentages Friday, while sellers unplugged Alliance Fiber Optics ( AFOP ), its stock falling by double digits, after both companies reported Q4 earnings late Thursday. Guess which did better. Both companies compete with bigger computer networking product makers Juniper Networks ( JNPR ) and much bigger Cisco Systems ( CSCO ). Cisco stock was flat in early afternoon trading Friday, while Juniper was up 1%. Arista stock rose as much as 16% Friday and was up 11%, near 65, in early afternoon trading in the stock market toda y, still 27% off an eight-month high of 88.56 set June 24. Meanwhile, Alliance’s Q4 results were hurt by cutbacks from its top customer, Alphabet ‘s ( GOOGL ) Google. Alliance stock fell as much as 17% Friday, touching a nearly 16-month low, and was down 15% in early afternoon trading, near 12. It’s 45% off a nearly two-year high set July 24 at 22.35. Helped by Microsoft ‘s ( MSFT ) Azure public cloud, Arista said Q4 earnings jumped 51% to 80 cents per share minus items, as revenue rose 41.5% to $245.4 million. Wall Street analysts polled by Thomson Reuters expected 61 cents and $241 million. Arista provides a network operating system, data center storage and other products. Arista’s non-GAAP gross profit margin settled at 64%, near the high end of the 62%-65% range it had forecast, but that was down from the 67.4% in Q4 2014 and 69% in Q1 2014, said FBN Securities analyst Shebly Seyrafi in a research note. “Therefore, there is some downside risk on the (gross margin) line going forward,” he wrote. Still, he and other analysts said Arista had solid momentum. Arista guided the Q1 non-GAAP gross margin to 62% to 65%, and revenue at $232 million to $240 million. Analysts expect Q1 EPS to rise 14% to 57 cents, on sales up 30% to $233.48 million. Reiterating Needham’s buy rating with a 105 price target, analyst Alex Henderson said in a Friday research note that “the news should only get better over 2016. “We think the shift to (faster-bandwidth) 25G architectures will accelerate Arista’s share gains,” he wrote. “We think Arista could pick up 3-5 points of market share on a base of 12%, driving continued stronger-than-forecast growth. This company is best in breed.” Seyrafi had noted that when FBN began covering Arista in September 2014, “one of the key bear points” was that Microsoft revenue was “quite robust,” comprising 11% of total Arista sales, as Microsoft built out Azure. He thought, though, that revenue for Arista might decline after the buildout. Instead, Arista said 2015 revenue from Microsoft topped $100 million, 12% of total sales, “so sales to MSFT do not appear to be slowing down,” said Seyrafi. FBN retained its outperform rating with an 80 price target for Arista stock. So what’s happening with little Alliance Fiber Optics, where adjusted EPS crashed 80% to 5 cents in Q4, while sales fell 13% to $16.4 million? Google “plummeted from 45% of revenue to 20% in (Q4) as it sharply reduced inventory at the behest of its new (Alphabet/Google) CFO (Ruth Porat) and cut capex by 40%,” said Needham’s Henderson in a separate research note Friday. Alliance “was caught in the crossfire,” he said. “But all indications are that that’s over. Google is expected to meaningfully increase spending in 2016, and the shift to 25G architectures should strongly improve AFOP’s results. … Despite the miss in (Q4), we are maintaining our 2016 and 2017 EPS estimates and reiterating our buy rating and 20 target price.” Needham expects adjusted EPS of $1.18 for 2016, up from 95 cents in 2015. Image provided by Shutterstock .