In my previous company we had one Indian employee. He had been in the company for years and did very solid work. When my boss hired another Indian group manager, he assigned the employee in question to that guys project. First the new group manager was not shaking hands with him, not communicating with him properly etc. We found out that the previous employee was from a lower caste, and that the new group manager refused to work with him. The group manager was then fired.

However this requires that the person in charge actually nips this kind of behaviour in the bud. And the group manager had a 15 year career in a very big company. So apparently he could do what he did without a problem for 15 years.

Of course the other employee (that we kept) was not happy about this "system".