After 20 years at the helm, John Chambers announced his long-anticipated retirement this morning. He'll be stepping down on July 26.

His replacement will be Chuck Robbins, who has been with Cisco since 1997 and was most recently senior vice president of worldwide operations. In a statement, Cisco lauds Robbins' role in the company's ongoing transformation, citing his hand in transforming the sales organization and his championing of the Sourcefire and Meraki acquisitions.

While Robbins sounds like an able candidate, many analysts had assumed Rob Lloyd, president of development and sales, was being groomed as Chambers' successor.

Robbins has been added to Cisco's board of directors as of May 1.

Chambers himself will stick around. He'll move to the role of executive chairman as of July 26 and will continue to play a customer-facing role at Cisco.

Chambers intends to focus on "country digitization," according to Cisco, which likely means he'll continue talking with national leaders, particularly in emerging markets. That's a role he seems to relish, judging by how often it comes up in his keynote speeches.

Chambers has been the company's de facto head salesman all along, and his continued presence on the front lines could provide some continuity as Cisco fight skirmishes on all fronts, as analysts noted in casual conversation at Interop last week.

Software-defined networking (SDN) seems likely to cause big changes in the way customers think about networks, whether Cisco succeeds in that area or not. White box switching might not threaten Cisco's networking franchise immediately — and Chambers has vowed to "crush" the nascent competition from that quarter — but it's drawing a lot of attention.

Hyperscale web players such as Facebook and Google have also increasingly become IT movers and shakers, pursuing in-house and open source infrastructure strategies that threaten Cisco's core business.

Cisco will provide more details during a press conference at 9:30 a.m. Pacific time, and SDxCentral intends to follow up with more coverage as well.