Abstract: A method and system for controlling data throughput in a network connecting two sites in which mixed communication protocols are employed, and in which the inter-site communication protocol is different than the intra-site communication protocol. A series of PING source messages are sent from a source storage device to a destination storage device via a network link. PING response messages, from the destination storage device via the network link, indicating receipt of each of the PING source messages are received and sampled. Round trip PING times for each of the PING source messages and corresponding PING response messages are determined and then sorted to separate PING timing data sampled when the network link was idle from PING timing data sampled when the network link was in use. The difference between the sampled idle PING timing data and the sampled busy PING timing data is calculated to obtain a delta PING time.