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网络流量波动，即使有环回

tag-icon • tag-icon linux-networking ubuntu-12.04 loopback network-traffic iperf
网络流量波动，即使有环回

我正在使用 iperf 工具在两台相同的机器（Dell Blade Server M620）上对我的网络接口进行基准测试。两台机器都给出了不同的结果。

  • 在第一台机器上，我运行服务器和客户端如下：

服务器 ==>iperf -s -B 172.17.250.200

Server listening on TCP port 5001 Binding to local address 172.17.250.200 TCP window size: 85.3 KByte (default) ----------------------------------------

新 shell 上的客户端==> iperf -c 172.17.250.200 -u -i l -b 250m，

WARNING:interval too small, increasing from 0.00 to 0.5 seconds -----------------------------------------------------------

Client connecting to 172.17.250.200, UDP port 5001
Sending 1470 byte datagrams 
UDP buffer size:  208 KByte (default)
------------------------------------------------------------
[  3] local 172.17.250.200 port 56853 connected with 172.17.250.200 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 0.5 sec  7.45 MBytes   125 Mbits/sec 
[  3]  0.5- 1.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.0- 1.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.5- 2.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  2.0- 2.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  2.5- 3.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  3.0- 3.5 sec  7.43 MBytes   125 Mbits/sec
[  3]  3.5- 4.0 sec  7.44 MBytes   125 Mbits/sec
[  3]  4.0- 4.5 sec  7.46 MBytes   125 Mbits/sec
[  3]  4.5- 5.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  5.0- 5.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  5.5- 6.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  6.0- 6.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  6.5- 7.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  7.0- 7.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  7.5- 8.0 sec  7.44 MBytes   125 Mbits/sec
[  3]  8.0- 8.5 sec  7.46 MBytes   125 Mbits/sec
[  3]  8.5- 9.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  9.0- 9.5 sec  7.46 MBytes   125 Mbits/sec
[  3]  9.5-10.0 sec  7.44 MBytes   125 Mbits/sec
[  3]  0.0-10.0 sec   149 MBytes   125 Mbits/sec`

  • 在第二台机器上，我以相同的配置运行，得到了以下结果：

    服务器==>iperf -s -B 172.17.250.190

    新 shell 上的客户端==>iperf -c 172.17.250.190 -u -i l -b 250m

    WARNING: interval too small, increasing from 0.00 to 0.5 seconds.
------------------------------------------------------------
Client connecting to 172.17.250.190, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size:  208 KByte (default)
------------------------------------------------------------
[  3] local 172.17.250.190 port 59887 connected with 172.17.250.190 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 0.5 sec  3.00 MBytes  50.3 Mbits/sec
[  3]  0.5- 1.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.0- 1.5 sec  7.45 MBytes   125 Mbits/sec
[  3]  1.5- 2.0 sec  7.45 MBytes   125 Mbits/sec
[  3]  2.0- 2.5 sec  7.05 MBytes   118 Mbits/sec
[  3]  2.5- 3.0 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  3.0- 3.5 sec  2.96 MBytes  49.7 Mbits/sec
[  3]  3.5- 4.0 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  4.0- 4.5 sec  2.97 MBytes  49.8 Mbits/sec
[  3]  4.5- 5.0 sec  2.96 MBytes  49.7 Mbits/sec
[  3]  5.0- 5.5 sec  2.88 MBytes  48.3 Mbits/sec
[  3]  5.5- 6.0 sec  2.88 MBytes  48.3 Mbits/sec
[  3]  6.0- 6.5 sec  2.89 MBytes  48.5 Mbits/sec
[  3]  6.5- 7.0 sec  2.92 MBytes  49.0 Mbits/sec
[  3]  7.0- 7.5 sec  2.94 MBytes  49.3 Mbits/sec
[  3]  7.5- 8.0 sec  2.93 MBytes  49.2 Mbits/sec
[  3]  8.0- 8.5 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  8.5- 9.0 sec  2.95 MBytes  49.5 Mbits/sec
[  3]  9.0- 9.5 sec  2.94 MBytes  49.3 Mbits/sec

为什么两台机器的结果会有差异，它们是相同的机器。一台机器显示稳定的 125Mbit/秒流量，而另一台显示波动的流量。？
我也尝试在两台机器上使用 iperf 的 IP 地址“127.0.0.1”，但仍然面临类似的问题。在环回的情况下，我认为流量不会通过 NIC，但环回仍然有波动。两台机器都运行 Ubuntu 12.04 Server 64bit。任何可能出错的帮助都将不胜感激。

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