Before revision:  Unfairness is common for some clients and they may always be regarded as outliers, so we also consider the fairness problem, and give randomized algorithms that embody lottery models, so that for each client j with its submitted parameter e_j , the expected number of connections for it is at least e_j.
After revision:  Unfairness is common for some clients and they may always be regarded as outliers, so we also consider variants of the aforementioned problems, namely fair robust fault-tolerant center problems. In these problems, each client j with its submitted parameter e_j , the expected number of connections for it is at least e_j.