2 identical virtual machines (with IP 192.168.0.232 and 192.168.0.231) with Debian 8 in hypervisor ESXi 5.5u2. Virtual network adapter - vmxnet3 (vmware-tools 9.4.0.27746 build-1399439) connected to one virtual network commutator.

Test network speed with iperf with one Windows 8.1 (192.168.0.3) - so slow with linux 192.168.0.232

Client connecting to 192.168.0.232, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.3 port 49242 connected with 192.168.0.232 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  13.5 MBytes  11.3 Mbits/sec

F:\Downloads\iperf-2.0.5-3-win32>iperf -c 192.168.0.231
------------------------------------------------------------
Client connecting to 192.168.0.231, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.3 port 49243 connected with 192.168.0.231 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   813 MBytes   682 Mbits/sec

From Linux 192.168.0.232

$ iperf -c 192.168.0.3
------------------------------------------------------------
Client connecting to 192.168.0.3, TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.232 port 33227 connected with 192.168.0.3 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.2 sec   423 MBytes   347 Mbits/sec

From Linux 192.168.0.231

iperf -c 192.168.0.3
------------------------------------------------------------
Client connecting to 192.168.0.3, TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.231 port 35334 connected with 192.168.0.3 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   861 MBytes   722 Mbits/sec

With Linux 192.168.0.231 192.168.0.232

$ iperf -c 192.168.0.232
------------------------------------------------------------
Client connecting to 192.168.0.232, TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.231 port 34759 connected with 192.168.0.232 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  18.7 GBytes  16.1 Gbits/sec

For testing deploy virtaul machine with  Windows 8.1 (192.168.0.4), connected with some virtual commutator.

C:\Users\user>C:\iperf\iperf.exe -c 192.168.0.232
------------------------------------------------------------
Client connecting to 192.168.0.232, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.4 port 49387 connected with 192.168.0.232 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  3.67 GBytes  3.15 Gbits/sec

C:\Users\user>C:\iperf\iperf.exe -c 192.168.0.231
------------------------------------------------------------
Client connecting to 192.168.0.231, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.4 port 49388 connected with 192.168.0.231 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  3.37 GBytes  2.90 Gbits/sec

Between Windows all is fine

F:\Downloads\iperf-2.0.5-3-win32>iperf -c 192.168.0.4
------------------------------------------------------------
Client connecting to 192.168.0.4, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.3 port 57614 connected with 192.168.0.4 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   754 MBytes   633 Mbits/sec

Where may be a problem ?

• Edited by Michail Safronov Monday, May 04, 2015 5:30 AM

Problem was on VMWare side, incorrect setting on virtaul switch.

• Proposed as answer by MeipoXuMicrosoft contingent staff, Moderator Wednesday, May 06, 2015 1:10 AM