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I have 2 servers connected with 10G cable between them directly. I need to know that the connection is good and it has indeed 10G throughput. I used IPERF to verify the bandwidth.

According to the test the bandwidth is 1.5-1.7 Gbits/sec. Does it mean the connection is 10G?

Server A is Windows 8.1 Pro 64bit

Server B is Windows 7 Enterprise 64bit

This is the output when A (192.168.10.100) is server and B (192.168.10.200) is client:

-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 192.168.10.200, port 63772
[  5] local 192.168.10.100 port 5201 connected to 192.168.10.200 port 63773
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.00   sec   170 MBytes  1.42 Gbits/sec
[  5]   1.00-2.00   sec   217 MBytes  1.82 Gbits/sec
[  5]   2.00-3.00   sec   217 MBytes  1.82 Gbits/sec
[  5]   3.00-4.00   sec   214 MBytes  1.80 Gbits/sec
[  5]   4.00-5.00   sec   217 MBytes  1.82 Gbits/sec
[  5]   5.00-6.00   sec   207 MBytes  1.74 Gbits/sec
[  5]   6.00-7.00   sec   199 MBytes  1.67 Gbits/sec
[  5]   7.00-8.00   sec   206 MBytes  1.73 Gbits/sec
[  5]   8.00-9.00   sec   192 MBytes  1.61 Gbits/sec
[  5]   9.00-10.00  sec   209 MBytes  1.75 Gbits/sec
[  5]  10.00-10.16  sec  30.3 MBytes  1.63 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-10.16  sec  0.00 Bytes  0.00 bits/sec                  sender
[  5]   0.00-10.16  sec  2.03 GBytes  1.72 Gbits/sec                  receiver

This is the output when B (192.168.10.200) is server and A (192.168.10.100) is client:

-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 192.168.10.100, port 55565
[  5] local 192.168.10.200 port 5201 connected to 192.168.10.100 port 55566
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-1.00   sec   170 MBytes  1.43 Gbits/sec
[  5]   1.00-2.00   sec   175 MBytes  1.47 Gbits/sec
[  5]   2.00-3.00   sec   175 MBytes  1.47 Gbits/sec
[  5]   3.00-4.00   sec   179 MBytes  1.50 Gbits/sec
[  5]   4.00-5.00   sec   181 MBytes  1.52 Gbits/sec
[  5]   5.00-6.00   sec   200 MBytes  1.68 Gbits/sec
[  5]   6.00-7.00   sec   176 MBytes  1.47 Gbits/sec
[  5]   7.00-8.00   sec   177 MBytes  1.48 Gbits/sec
[  5]   8.00-9.00   sec   186 MBytes  1.56 Gbits/sec
[  5]   9.00-10.00  sec   179 MBytes  1.50 Gbits/sec
[  5]  10.00-10.04  sec  6.42 MBytes  1.46 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  5]   0.00-10.04  sec  0.00 Bytes  0.00 bits/sec                  sender
[  5]   0.00-10.04  sec  1.76 GBytes  1.51 Gbits/sec                  receiver
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  • 1
    It is faster than 1 Gbps, so the connection must be 10 Gbps, although you aren't transferring nearly that fast, but there are other reasons for that. Servers are off-topic here, and you could ask why on Server Fault.
    – Ron Maupin ♦
    Commented Aug 9, 2016 at 18:14

1 Answer 1

Reset to default
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That could be issue with Window Auto-Tuning which is implemented in windows. Due to default settings size of window never will be bigger than 256 KB. To switch off Windows Auto-Tuning you need to isse command:

netsh int tcp set global autotuninglevel=disabled
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