发送方背靠背发送UDP包。接收方接收后，分别提取接收包的时间，前后两包相减得到延迟。包的大小除延迟得到瓶颈带宽。-The sender sends a UDP packet back to back. After receiving the recipient, receiving packets were extracted from the time before and after subtracting two packets of delay. In addition to the size of the packet delay to get the bandwidth bottleneck.