A first network client requests initiation of a data transfer with a second network client. An admission control facility (ACF) responds to the initiation request by performing admission analysis to determine whether to initiate the data transfer. The ACF sends one or more packets to the second network client. In response, the second network client sends acknowledgment packets back to the ACF. The ACF performs admission analysis based on the packets sent and the acknowledgment packets, and determines whether the data transfer should be initiated based on the analysis. The admission analysis may be based on a variety of factors, such as the average time to receive an acknowledgment for each packet, the variance of the time to receive an acknowledgment for each packet, a combination of these factors, or a combination of these and other factors.