I had a guy on my team who was very capable but did not have the right last name, he was being harassed for promotions for 4-5 years. On the other hand the manager class was entirely "jain, gupta, sharma, verma". I know of a specific case where the same manager had one of his relatives transferred from another branch and then promoted to manager on a different team in the same branch. This was all very hush-hush, I know of it because I overheard them talking about it. This is not some local tidbit software company, this is a company you HAVE heard about.
But it is not just caste based discrimination. There's also linguistic and region based discrimination because there is a lot of regional and linguistic diversity in India. If you travel a few hundred miles in any direction, the language and culture completely change. I have seen teams being formed around states and languages, and they will not let anyone else come into their in group. I have seen teams with extreme left ideologies that will not let anyone else in their team.
I don't believe dalits are any different, they also engange in these practices when they can and I know about people who have suffered from that situation as well.
Everyone's naked in this bath house.