The connection based TCP protocol provides reliable packet delivery, but it takes certain overhead compare to the connection-less UDP protocol. Thus, 3GPP devise the upper-layer RLC protocol which provides reliability based upon the UDP protocol. Consequently, each implement of a base station and/or mobile terminal require the development of the RLC protocol, and it must qualify various interoperable tests. In this paper, we implement a testbed which verifies the RLC protocol under various packet losses/inversion circumstances of networks. Finally, we propose our testbed as the RLC protocol tester for the developments.