So, if you buy a server with say a 1.6Gbps connection in this customers case, you might want to test you have the bandwidth you need, for instance to be resilient against small DOS and DDOS in the sub 500mbit -1000mbit range.
Here is how I did it (quick summary)
$ iperf -c somedestipiwanttospeedtest-censored -p 80 -P 2 -b 100m WARNING: option -b implies udp testing ------------------------------------------------------------ Client connecting to somedestipiwanttospeedtest-censored, UDP port 80 Sending 1470 byte datagrams UDP buffer size: 208 KByte (default) ------------------------------------------------------------ [ 4] local someipsrc port 53898 connected with somedestipiwanttospeedtest-censored port 80 [ 3] local someipsrc port 50460 connected with somedestipiwanttospeedtest-censored port 80 [ ID] Interval Transfer Bandwidth [ 4] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 4] Sent 85471 datagrams [ 3] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 3] Sent 85471 datagrams [SUM] 0.0-10.0 sec 240 MBytes 201 Mbits/sec [ 3] WARNING: did not receive ack of last datagram after 10 tries. [ 4] WARNING: did not receive ack of last datagram after 10 tries. $ iperf -c somedestipiwanttospeedtest-censored -p 80 -P 10 -b 100m WARNING: option -b implies udp testing ------------------------------------------------------------ Client connecting to somedestipiwanttospeedtest-censored, UDP port 80 Sending 1470 byte datagrams UDP buffer size: 208 KByte (default) ------------------------------------------------------------ [ 12] local someipsrc port 50725 connected with somedestipiwanttospeedtest-censored port 80 [ 5] local someipsrc port 40410 connected with somedestipiwanttospeedtest-censored port 80 [ 6] local someipsrc port 51075 connected with somedestipiwanttospeedtest-censored port 80 [ 4] local someipsrc port 58020 connected with somedestipiwanttospeedtest-censored port 80 [ 3] local someipsrc port 50056 connected with somedestipiwanttospeedtest-censored port 80 [ 7] local someipsrc port 57017 connected with somedestipiwanttospeedtest-censored port 80 [ 8] local someipsrc port 49473 connected with somedestipiwanttospeedtest-censored port 80 [ 9] local someipsrc port 50491 connected with somedestipiwanttospeedtest-censored port 80 [ 10] local someipsrc port 40974 connected with somedestipiwanttospeedtest-censored port 80 [ 11] local someipsrc port 38348 connected with somedestipiwanttospeedtest-censored port 80 [ ID] Interval Transfer Bandwidth [ 12] 0.0-10.0 sec 114 MBytes 95.7 Mbits/sec [ 12] Sent 81355 datagrams [ 5] 0.0-10.0 sec 114 MBytes 95.8 Mbits/sec [ 5] Sent 81448 datagrams [ 6] 0.0-10.0 sec 114 MBytes 95.8 Mbits/sec [ 6] Sent 81482 datagrams [ 4] 0.0-10.0 sec 114 MBytes 95.7 Mbits/sec [ 4] Sent 81349 datagrams [ 3] 0.0-10.0 sec 114 MBytes 95.7 Mbits/sec [ 3] Sent 81398 datagrams [ 7] 0.0-10.0 sec 114 MBytes 95.8 Mbits/sec [ 7] Sent 81443 datagrams [ 8] 0.0-10.0 sec 114 MBytes 95.7 Mbits/sec [ 8] Sent 81408 datagrams [ 9] 0.0-10.0 sec 114 MBytes 95.8 Mbits/sec [ 9] Sent 81421 datagrams [ 10] 0.0-10.0 sec 114 MBytes 95.7 Mbits/sec [ 10] Sent 81404 datagrams [ 11] 0.0-10.0 sec 114 MBytes 95.8 Mbits/sec [ 11] Sent 81427 datagrams [SUM] 0.0-10.0 sec 1.11 GBytes 957 Mbits/sec It looks like you are getting the bandwidth you desire, when repeating the test with 20 connections I can see the bandwidth hits a total of 2.01Gbits/sec # iperf -c somedestipiwanttospeedtest-censored -p 80 -P 20 -b 100m WARNING: option -b implies udp testing ------------------------------------------------------------ Client connecting to somedestipiwanttospeedtest-censored, UDP port 80 Sending 1470 byte datagrams UDP buffer size: 208 KByte (default) ------------------------------------------------------------ [ 22] local someipsrc port 44231 connected with somedestipiwanttospeedtest-censored port 80 [ 4] local someipsrc port 55259 connected with somedestipiwanttospeedtest-censored port 80 [ 7] local someipsrc port 49519 connected with somedestipiwanttospeedtest-censored port 80 [ 3] local someipsrc port 45301 connected with somedestipiwanttospeedtest-censored port 80 [ 6] local someipsrc port 48654 connected with somedestipiwanttospeedtest-censored port 80 [ 5] local someipsrc port 33666 connected with somedestipiwanttospeedtest-censored port 80 [ 8] local someipsrc port 33963 connected with somedestipiwanttospeedtest-censored port 80 [ 9] local someipsrc port 39593 connected with somedestipiwanttospeedtest-censored port 80 [ 10] local someipsrc port 36229 connected with somedestipiwanttospeedtest-censored port 80 [ 11] local someipsrc port 36331 connected with somedestipiwanttospeedtest-censored port 80 [ 14] local someipsrc port 54622 connected with somedestipiwanttospeedtest-censored port 80 [ 13] local someipsrc port 36159 connected with somedestipiwanttospeedtest-censored port 80 [ 12] local someipsrc port 53881 connected with somedestipiwanttospeedtest-censored port 80 [ 15] local someipsrc port 43221 connected with somedestipiwanttospeedtest-censored port 80 [ 16] local someipsrc port 60284 connected with somedestipiwanttospeedtest-censored port 80 [ 17] local someipsrc port 49735 connected with somedestipiwanttospeedtest-censored port 80 [ 18] local someipsrc port 43866 connected with somedestipiwanttospeedtest-censored port 80 [ 19] local someipsrc port 44631 connected with somedestipiwanttospeedtest-censored port 80 [ 20] local someipsrc port 56852 connected with somedestipiwanttospeedtest-censored port 80 [ 21] local someipsrc port 59338 connected with somedestipiwanttospeedtest-censored port 80 [ ID] Interval Transfer Bandwidth [ 22] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 22] Sent 85471 datagrams [ 4] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 4] Sent 85449 datagrams [ 7] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 7] Sent 85448 datagrams [ 3] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 3] Sent 85448 datagrams [ 6] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 6] Sent 85449 datagrams [ 5] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 5] Sent 85448 datagrams [ 8] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 8] Sent 85453 datagrams [ 9] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 9] Sent 85453 datagrams [ 10] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 10] Sent 85454 datagrams [ 11] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 11] Sent 85456 datagrams [ 14] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 14] Sent 85457 datagrams [ 13] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 13] Sent 85457 datagrams [ 12] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 12] Sent 85457 datagrams [ 15] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 15] Sent 85460 datagrams [ 16] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 16] Sent 85461 datagrams [ 17] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 17] Sent 85462 datagrams [ 18] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 18] Sent 85464 datagrams [ 19] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 19] Sent 85467 datagrams [ 20] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 20] Sent 85467 datagrams [ 21] 0.0-10.0 sec 120 MBytes 101 Mbits/sec [ 21] Sent 85467 datagrams [SUM] 0.0-10.0 sec 2.34 GBytes 2.01 Gbits/sec The last test I did used 2 connections only at 500mbit each; # iperf -c somedestipiwanttospeedtest-censored -p 80 -P 2 -b 500m WARNING: option -b implies udp testing ------------------------------------------------------------ Client connecting to somedestipiwanttospeedtest-censored, UDP port 80 Sending 1470 byte datagrams UDP buffer size: 208 KByte (default) ------------------------------------------------------------ [ 4] local someipsrc port 60841 connected with somedestipiwanttospeedtest-censored port 80 [ 3] local someipsrc port 51495 connected with somedestipiwanttospeedtest-censored port 80 [ ID] Interval Transfer Bandwidth [ 4] 0.0-10.0 sec 570 MBytes 479 Mbits/sec [ 4] Sent 406935 datagrams [ 3] 0.0-10.0 sec 570 MBytes 479 Mbits/sec [ 3] Sent 406933 datagrams [SUM] 0.0-10.0 sec 1.11 GBytes 957 Mbits/sec