Slow connectivity to internet from VMs

asked 2015-05-21 22:50:45 -0500

linusali gravatar image

I have installed openstack using fuel 6 on a 8 node physical cluster. Intitially when I installed, every thing worked with out any problem, including the network connectivity to and from internet.

But when I re-deployed the cluster, the network speed to and from internet slowed down dramatically. I tried all sorts of ethtool settings, but didn't gave any results. The download speed is around 10Mbps and upload is around 3Mbps.

Interestingly the connectivity between VM to VM or VM to external nodes with in the local network or to a node on a second interface of the firewall is running perfectly fine as expected. Also I have checked the speed from the host machine itself and was giving the full 50Mbps both ways to it. I am really stumped, any help would be highly appreciated.

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Check the MTU. If you are using a gre or vxlan tunnel, then you may need to either set the mtu to 1450 on the VM, or you can set the MTU on the interfaces that the tunnel runs through to 1550.

jdexter gravatar imagejdexter ( 2015-05-29 11:29:36 -0500 )edit

Thanks jdexter, I have tried all those tricks and tips, but non worked. It turns out that some how the speedtest tool with in a KVM vm environment is giving the problem. The VMs are running perfectly fine with full network speed.

So moral of the story is not to use speedtest tool, but use iperf

linusali gravatar imagelinusali ( 2015-06-16 02:45:50 -0500 )edit