Poor network performance on OpenStack GRE or VXLAN tenant network

Issue

• Network Bandwidth of OpenStack Virtual Machine is Too Slow
• My RHOS instances are too slow to communicate from outside
• Bandwidth of compute and virtual machines calculated by iperf3 tool is drastically different:
• MTU size is wrong causing packet to drop and ssh commands to hang on OpenStack instances

Compute Node

[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec  1.01 GBytes   866 Mbits/sec  226         sender
[  4]   0.00-10.00  sec  1.01 GBytes   866 Mbits/sec              receiver

Virtual Machine

[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-15.50  sec   256 KBytes   135 Kbits/sec   76         sender
[  4]   0.00-15.50  sec   128 KBytes  67.6 Kbits/sec              receiver