1. Growth probability for sr managers and principal engineers for next level. How long will it take, in otherwords would they stagnate for long time?
I'm only an IC, but from what I've seen, promotions for Sr Manager and higher are far and few between, and it takes a long time. Principal or Distinguished Engineers are pretty much the top of the ladder unless they move over to the management ladder. They get RSU's instead of promotions and pay increases.
2. I have seen many people leave and come back to Cisco, will they offered better salary. Is this not exploiting.
If you've seen many people leave and come back, why are you asking the 3rd and 4th questions? As to exploiting, who are you asking is being exploited or who is doing the exploiting? I feel that Cisco is doing the exploiting of employees and contractors.
As a contractor, Cisco sets a "bill rate" for the consulting company and it never changes until the role is terminated. No consulting company is going to pay their employee more, i.e. give them a raise, without getting more from the client, and Cisco is not going to raise the bill rate, so the only way for that contractor to get a pay increase is to leave the contract and go somewhere else. And potentially come back.
As an employee, pay raises are slow and based on each year's budget for increases. Each year's budget can vary greatly from year to year meaning that raises rarely match inflation, so employees are forced to leave, & possibly come back, to get pay that matches the pay of new/recent hires who come in at market rates.
The biggest problem w/ leaving and coming back is that it resets your seniority for PTO purposes. Cisco increases the amount of PTO you can accrue based on years of service for your current tenure. For other seniority calculations, your total years of service are used. I'm not sure how the years of service are calculated for additional weeks of severance when being laid off to be able to say if it's like the PTO calculation where it's the current tenure, or like early retirement where it's the combined years of service.
3. Will Cisco ever rehires people it laid off
Yes. It's frequently done. I know there are people who've been laid off more than once who've returned. And, yes, they've got a better salary in the new role than the previous role.
4. For those who are coming back, will there be an interview process they have to. undergo?
I'm sure that depends on the hiring manger, as well as if the person being hired is coming back as a contractor and then converting to employee or is being hired directly as an employee. In my experience on the teams that I've been part of, ex-Cisco employees are still interviewed for direct-hire roles & for contractor roles. As to contractor-to-employee conversions, I've seen managers just convert the contractor w/o an interview, but most of the conversions I've seen, the managers opened job reqs (either for internal hire or internal/external hire) and went through the interview process w/ all candidates.
In my personal case, I started as a contractor and part of my contractor interview process I was asked if I'd be willing to convert to an employee as the goal for this role was for it to be an employee role, but they had to go the contractor route first to get it approved and staffed. Then the previous person didn't work out and was terminated making it more imperative to use the contractor "try-before-you-buy" model to make sure the next person was a good fit w/in the team. After several yrs in the role, mainly due to that team's decision to convert contractors in order of seniority (first-in-first-converted), my turn finally came around and the manager started the process as a direct conversion which would have required no interview. We were waiting on my background investigation to be completed when Cisco went into a hiring freeze and they blocked my conversion. After 18 months, the freeze was lifted and the manager decided to do the external hire route and I was forced to interview & compete against 3-5 other candidates even though they really wanted to "hire" me.