Where would Cisco (and its CEO) be without her?

Cisco CEO John Chambers speaks during the 2011 International Consumer Electronics Show (CES) in Las Vegas.
Jacob Kepler | Bloomberg | Getty Images

Debbie Gross was thrilled when Cisco Systems offered her a $36,000 salary to join as executive assistant in 1991. She didn't know much about the 560-person company, but at age 35 she was up for a new challenge, and the pay amounted to a solid raise from her previous gig.

As Cisco celebrates its 30th anniversary this month, Gross stands among the longest-tenured of the technology company's 74,000-plus employees. And she's spent her 2½ decades there working for a single boss: John Chambers.

"I had no idea that John would ultimately be CEO some day," said Gross, now 59, reflecting on her career working for one of Silicon Valley's most powerful figures. "They were at a point of desperation when I was interviewed. I was the 17th candidate he interviewed over the course of a month."

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When Gross came to Cisco, the Internet didn't exist in any meaningful way. Chambers, a senior vice president at the time, had only been at the company for two months. The campus consisted of three buildings in East Palo Alto, California. The stock was trading at about 15 cents on a split-adjusted basis.

It could reasonably be argued that few people in the technology world have worked harder over the past 24 years than Debbie Gross. Her boss, who was promoted to CEO in January 1995, is the longest-standing top executive among Silicon Valley's major tech companies.

Chambers is a traveling machine, and he's meeting people running not just the biggest businesses in the world; but also the largest countries. Among Gross' roster of responsibilities is making sure Chambers is prepared for every briefing, conference, sporting event and sales pitch. He needs details on everyone in the room or on the golf course.

"You'd be nauseated to see what we put together for him," Gross said from the company's sprawling headquarters in San Jose. "He doesn't really know what he's doing until he goes on the plane. Our teams are constantly putting together materials for him to review."

Debbie Gross and John Chambers.
Source: Cisco

Some stories Gross is even willing to share. Like the dinner two years ago in San Jose, featuring California Gov. Jerry Brown speaking to a group of CEOs. Putting together a packet on Brown was the easy part. More time consuming was gathering all the relevant state and local initiatives that the governor might discuss. And, of course, the seating chart, because Chambers needed personal information on his dinner mates.

Sitting next to him at the meal was another tech CEO, Aart de Geus of Synopsys, whose assistant was a friend of Gross'.

"She called me up two hours after the event and said, `Now my CEO wants exactly what you did for John,'" Gross said. "He now uses his own event briefing the same way we do for John."

In an emailed statement, Chambers had this to say about Gross: "Debbie has always been and continues to be a true business partner; she makes it a point to know the business, what my priorities are and she has the ability to represent me as well as Cisco in the absolute best professional manner."

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While supporting Chambers is more than a full-time job, even with two assistants helping her out, Gross' work isn't limited to the C-suite. She leads training sessions for employees across the company in administrative roles and teaches courses to help administrators put processes in place at large organizations.

She's also arbiter of sporting events tickets. Chambers has season passes for the San Francisco Giants, Oakland A's, San Jose Sharks, Golden State Warriors, San Francisco 49ers as well as Stanford University football and basketball. For those keeping score, that's approximately 275 home games a year spread across the four major sports.

Chambers doesn't make it to many of those events, and it's Gross' job is to make sure employees get their turn. "I have more people who love me because of the tickets," she said.

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Gross was born in Jackson, Mississippi, and moved to Kansas for high school. Her father was in the lumber insurance business, and was transferred to the Bay Area in the early 1970s.

Gross spent some time at a local junior college, but was thrust into the labor market without a degree, first at five and dime stores, and then in advertising. "I have a degree in common sense," she said.

From there she went into office management at a tech company, before landing her first executive assistant position in the 1980s at a PC board provider. She was making $26,000 a year when she saw a listing for the Cisco job in the San Jose Mercury News.

Gross is the first to admit that Cisco has been very good to her. The stock has multiplied 184-fold since her arrival and was such a rocket ship through the 1990s that it split almost annually during her first nine years. Her first purchase from stock gains was a $200 leather jacket. Then came a Ford Explorer SUV, followed by the down payment on a new house for her and her husband. Most recently, she cashed in some equity to buy a Corvette Stingray.

Of course, the past 14 years have been anything but a straight shot for Cisco. The shares crashed with the rest of the tech universe in the early 2000s, before sustaining a nice rally in the middle of the decade. But then came the financial crisis followed by a dramatic shift to cloud computing that's eating into big chunks of Cisco's traditional computer-networking business. At Thursday's closing price of $27.65, the stock was 66 percent off its bubble-era record from 2000.

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"Back then, the stock was phenomenal," Gross said. After the crash, "we were depressed at $32. Now we're happy at $27." The shares are up 23 percent this year.

Perhaps the greatest irony of Gross' job is that, while her boss has led the company that's built much of the plumbing for the modern-day Internet, Chambers is somewhat of a technology novice when it comes to the gadgets driving the traffic.

He was a BlackBerry devotee long after the tech world had moved to touchscreen smartphones, and he didn't really pick up texting until the last couple years—Gross often still communicates with him via voicemail.

He now loves Apple devices and is addicted to his iPhone. About two years ago, after Chambers purchased an iPad, Gross showed him an app called Pandora that would stream his favorite tunes from the 1970s.

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"I hit play, and he said,`That's really cool.' I was tickled about the fact that I could show him things he didn't know." She also showed him how to increase the font size and brighten the screen.

As another year comes to a close, the tech world keeps asking the question: How much longer will John Chambers stay? Others of his generation have taken a backseat. Oracle's Larry Ellison announced in September that he was stepping down as CEO of the company he founded 37 years ago, and Steve Ballmer ended his 14-year reign as Microsoft CEO in February.

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Among the top 10 publicly traded U.S. technology companies by revenue, only founder Jeff Bezos has been CEO longer than Chambers. Bezos started and assumed the helm of the online retailer the year before Chambers' promotion to CEO.

Chambers, who turned 65 in August, hasn't talked publicly about succession since 2012, when he told Bloomberg News that he may retire in two to four years.

The company isn't commenting beyond that, and Gross certainly isn't offering any clues. But she is planning for life after Cisco, which will involve greater focus on the training work she does for administrators and more public speaking engagements.

For now, Gross is clear that she's sticking with Chambers until they've finished what they started.

"We're a team. I've let him know that I'll be there for him until such time as things change," she said. "He loves the company. As long as he's here, I'll be here with him."