Reliable transport protocol like TCP has served well the wired Internet where the packet losses are mainly due to congestion, but is not ready for Mobile IP wired-cum-wireless environments where the significant packet losses are due to bit errors and handoffs. In this paper, we have investigated the performance of TCP among the various TCP variants. We have observed both TCP senders (Newreno and Vegas) and TCP receivers (Base and Delayed-Ack). Using ns-2, we have evaluated the TCP throughput and packet delay over a single TCP connection. The simulation results suggest that a particular combination (one TCP sender with one TCP receiver) of TCP shows the best result in such Mobile IP networks.