The main reason is Google's size. "Google has the mindshare and capital resources that it can be as big a threat as it desires to be," Kerravala said.

The Google threat to Cisco could be especially acute compared with Google's threat to other companies, since Cisco has a dual mission of keeping its traditional enterprise customers and service providers happy and well-supplied with networking gear, while also seeking to service consumers, especially with video technology.

Cisco in March announced plans to for its Flip handheld camera technology and has said it is developing a consumer telepresence product.

"We think video is going to be very key in driving the next level of collaboration ... with Internet video, desktop video ... and consumer telepresence," said Padmasree Warrior, Cisco's CTO, who joined Dennerline on today's conference call.

So while Cisco clearly recognizes its audience as both business customers and consumers, a more pertinent question is whether Google intends to go beyond its consumer business with its Voice and Wave products, taking both services into business settings.