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 s