I used iperf -c FOO_NODE -t 120 -i 10
to test the network with the other node FOO_NODE, sometimes I get the result like:
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 3.75 MBytes 3.15 Mbits/sec
[ 3] 10.0-20.0 sec 3.75 MBytes 3.15 Mbits/sec
[ 3] 20.0-30.0 sec 3.62 MBytes 3.04 Mbits/sec
[ 3] 30.0-40.0 sec 3.88 MBytes 3.25 Mbits/sec
[ 3] 40.0-50.0 sec 4.25 MBytes 3.57 Mbits/sec
[ 3] 50.0-60.0 sec 3.75 MBytes 3.15 Mbits/sec
[ 3] 60.0-70.0 sec 4.00 MBytes 3.36 Mbits/sec
[ 3] 70.0-80.0 sec 3.62 MBytes 3.04 Mbits/sec
[ 3] 80.0-90.0 sec 3.25 MBytes 2.73 Mbits/sec
[ 3] 90.0-100.0 sec 3.75 MBytes 3.15 Mbits/sec
[ 3] 100.0-110.0 sec 4.38 MBytes 3.67 Mbits/sec
[ 3] 110.0-120.0 sec 3.50 MBytes 2.94 Mbits/sec
[ 3] 0.0-120.5 sec 45.6 MBytes 3.18 Mbits/sec
All are in range of 3~6
But sometimes I got the result like this:
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 54.0 MBytes 45.3 Mbits/sec
[ 3] 10.0-20.0 sec 56.6 MBytes 47.5 Mbits/sec
[ 3] 20.0-30.0 sec 58.2 MBytes 48.9 Mbits/sec
[ 3] 30.0-40.0 sec 58.2 MBytes 48.9 Mbits/sec
[ 3] 40.0-50.0 sec 59.4 MBytes 49.8 Mbits/sec
[ 3] 50.0-60.0 sec 57.5 MBytes 48.2 Mbits/sec
[ 3] 60.0-70.0 sec 58.0 MBytes 48.7 Mbits/sec
[ 3] 70.0-80.0 sec 58.2 MBytes 48.9 Mbits/sec
[ 3] 80.0-90.0 sec 58.8 MBytes 49.3 Mbits/sec
[ 3] 90.0-100.0 sec 58.2 MBytes 48.9 Mbits/sec
[ 3] 100.0-110.0 sec 57.6 MBytes 48.3 Mbits/sec
[ 3] 110.0-120.0 sec 59.2 MBytes 49.7 Mbits/sec
[ 3] 0.0-120.2 sec 694 MBytes 48.5 Mbits/sec
All are in range of 40~50.
And 3~6 happened more often.
I tested that from a node in ec2 to a node in other cloud server center. And I don't think there'll be much congestion cause both of them are less used.
This's weird. What's the problem?