TCP is a prominent protocol used by Internet community. Among the TCP implementations, TCP Reno is widely used, and TCP Vegas is a protocol under active research and is expected to replace TCP Reno. TCP Vegas performance is better than other TCP implementations when is in operation separately, independent of other protocols. But its performance is affected when interoperated with TCP Reno. In this paper modifications to congestion avoidance procedure of TCP Vegas are proposed to solve the interoperability problem. Modifications proposed allow TCP Vegas to use its share of bandwidth efficiently. For simulation NS2 is used.