Open Stack

Hi,

I have a three node Icehouse Cluster running on CentOS 6.5 ( using RDO yum
repostories but not installed via packstack ).  We are using GRE Tunnels,
so experience the issues where some packets are truncated because they
exceed the 1500 mtu size.

>From what I have read most people are reducing the size of the guests MTU
to work around the issue.  We thought another another approach would
increasing the MTU size available.

So for the appropriate ports we have set the MTU to 9000 on the switch.

If we change the MTU on all nodes to 9000, then all pre-existing instance
appear to work as expected (both before and after rebooting one or all
nodes).  But launching a new instance is always stuck at scheduling.
Nothing is being recorded in /var/log/nova/scheduler.log on the controller.

If we revert all nodes back to MTU 1500 all starts working again.

Does anyone have suggestions as to what I am missing ?
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