Cisco Systems's senior official in charge of data center, switching and services is leaving after 15 years at the networking company to pursue other opportunities.

Jayshree Ullal, senior vice president of Cisco's Data Center, Switching and Services Group, said her departure was her own decision, although she didn't announce any future plans.

Ullal is the third high-level executive to leave in 15 months, which will pose some challenges for Cisco as it grows into a more generic IT vendor beyond its role as a networking company. Charles Giancarlo, the chief development officer, left in late December to join an investment firm, while Mike Volpi, senior vice president in charge of service providers and routing, left in February 2007.

"I think Cisco, as it becomes more of an IT vendor, needs to bring in some new talent," said Zeus Kerravala, an analyst at Yankee Group Inc. "You'll see more leadership changes at Cisco over the next couple of years."

He said Cisco is still the strongest networking vendor, but the company has outlined broad plans to be a more generic IT vendor, offering applications and computing technologies. "It's healthy for Cisco to have leadership changes as it transforms itself."

In a blog, Ullal wrote on Friday, "I hope to re-kindle passions for my 'next new gig' this summer and make an informed decision later this year."

Ullal will be replaced by John McCool, who will report directly to Cisco CEO John Chambers, according to the company's blog for Cisco's leadership. "Jayshree's contributions to the networking industry and the respect she garners across the organization ensures that she will always remain part of the extended Cisco family," wrote Elizabeth McNichols, director of corporate communications. "We wish you the best of luck, Jayshree...You will be missed."

Ullal noted that she joined Cisco in 1993, as a part of Cisco's first acquisition of Crescendo Communications when Cisco was largely a router company. She said the company grew from about US$1 billion in annual revenues back then to nearly US$40 billion today, with its hands in a variety of networking technologies.

"My loyalty and affection to Cisco, CEO John Chambers and my teams made this a very difficult and lengthy decision process," Ullal said in the blog.

She noted that teams under her direction have generated 1,500 patents and have introduced market-leading data center technologies. In all, Cisco has sold 1 million 10 gigabit Ethernet ports across switches and routers, a key milestone of 10 gigabit Ethernet adoption for data centers, she said.