install four test systems on the same ESXi 6.0 update 2 FreeBSD10.3 IP 10.10.10.103 RHEL66 IP 10.10.10.66 FreeBSD10.3 RHEL66 netowrk Cards are vmxnet3, these test OS all in the same ESXi host, the same vswitcher, the same subnet, otherwise no adjustment is installed by default When FreeBSD running iperf as server : iperf -s Any other client iperf -c 10.10.10.103 (FreeBSD 10.3 IP address) Speed is generally 7.xG But RHEL66 run iperf as server: iperf -s Any client iperf -c 10.10.10.66 (RHEL66 IP address) Speeds of up to 30G, 38G highest And then on another host ESXi6.0 update2 test, the situation is still so FreeBSD run ipers -c as client ,speed can reach 38G But FreeBSD run iperf -s as server, the speed only 8G test result: root@freebsd103:~ # uname -a FreeBSD freebsd103 10.3-RELEASE-p2 FreeBSD 10.3-RELEASE-p2 #0: Wed May 4 06:03:51 UTC 2016 root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64 root@freebsd103:~ # root@freebsd103:~ # iperf -s ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 64.0 KByte (default) ------------------------------------------------------------ [ 4] local 10.10.10.103 port 5001 connected with 10.10.10.66 port 38535 [ ID] Interval Transfer Bandwidth [ 4] 0.0-10.0 sec 9.14 GBytes 7.85 Gbits/sec ^Croot@freebsd103:~ # iperf -c rhel66 ------------------------------------------------------------ Client connecting to rhel66, TCP port 5001 TCP window size: 32.5 KByte (default) ------------------------------------------------------------ [ 3] local 10.10.10.103 port 10056 connected with 10.10.10.66 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 45.2 GBytes 38.8 Gbits/sec root@freebsd103:~ #
*** This bug has been marked as a duplicate of bug 209658 ***