Various transmission control protocol (TCP) enhancement schemes have been proposed to improve TCP performance over mixed wired/wireless networks. Among the different kinds of TCP enhancement schemes, end-to-end TCP enhancement schemes have the lowest implementation complexity and do not violate the semantics of TCP. Recently the latest version of Linux (version 2.6.18) has included a popular end-to-end TCP enhancement scheme, TCP Veno, for network communications over wireless networks . This paper is to investigate the performance of the loss differentiation algorithm in Veno over different mixed wired/wireless networks. Simulation results show that the original parameter setting of Veno in  is not optimal and the optimal parameter setting is highly affected by the external wireless loss probability.