我有两台机器（两台都是Centos 7.3）通过1G交换机连接。 当我使用iperf测量macines之间的UDP吞吐量时，它提供了大约850 Mbit / s。 但是，当我测量组播 UDP时，会导致类似于95 Mbit / s（几乎减慢10倍）的结果。
这有什么可能的原因？
单播样本输出：
$ iperf -c 192.168.1.11 -u -b 9900m -fm -i 5 -t 30 -w 1m ------------------------------------------------------------ Client connecting to 192.168.1.11, UDP port 5001 Sending 1470 byte datagrams, IPG target: 1.19 us (kalman adjust) UDP buffer size: 2.00 MByte (WARNING: requested 1.00 MByte) ------------------------------------------------------------ [ 3] local 192.168.1.208 port 52738 connected with 192.168.1.11 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 5.0 sec 503 MBytes 845 Mbits/sec [ 3] 5.0-10.0 sec 507 MBytes 850 Mbits/sec [ 3] 10.0-15.0 sec 500 MBytes 839 Mbits/sec [ 3] 15.0-20.0 sec 499 MBytes 837 Mbits/sec [ 3] 20.0-25.0 sec 497 MBytes 834 Mbits/sec [ 3] 25.0-30.0 sec 501 MBytes 841 Mbits/sec [ 3] 0.0-30.0 sec 3008 MBytes 841 Mbits/sec [ 3] Sent 2145384 datagrams [ 3] Server Report: [ 3] 0.0-30.0 sec 3008 MBytes 841 Mbits/sec 0.406 ms 0/2145384 (0%)
多播的示例输出：
$ iperf -c 239.255.1.3 -u -b 990m -fm -i 5 -t 30 -w 1m ------------------------------------------------------------ Client connecting to 239.255.1.3, UDP port 5001 Sending 1470 byte datagrams, IPG target: 11.88 us (kalman adjust) Setting multicast TTL to 1 UDP buffer size: 2.00 MByte (WARNING: requested 1.00 MByte) ------------------------------------------------------------ [ 3] local 192.168.1.208 port 53248 connected with 239.255.1.3 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 5.0 sec 57.2 MBytes 95.9 Mbits/sec [ 3] 5.0-10.0 sec 57.0 MBytes 95.6 Mbits/sec [ 3] 10.0-15.0 sec 56.4 MBytes 94.6 Mbits/sec [ 3] 15.0-20.0 sec 56.4 MBytes 94.6 Mbits/sec [ 3] 20.0-25.0 sec 56.4 MBytes 94.6 Mbits/sec [ 3] 25.0-30.0 sec 54.5 MBytes 91.4 Mbits/sec [ 3] 0.0-30.0 sec 338 MBytes 94.3 Mbits/sec [ 3] Sent 240946 datagrams
一些观察：
iptraf-ng发送方的stream量已经很低。 但是我不知道我能否信任它。 Upd：开关：Netgear GS108（非托pipe）