I installed Grizzly multi node setup in ubuntu 12.04 LTS with kernel 3.5. But I have problem with instance getting IP and external network connectivity. Surfing over this issue, I found kernel version 3.2 and higher should not be used for OVS with GRE tunneling. Is it true? If it is can anyone tell me which version of kernel should I use for openstack- Grizzly setup with GRE tunneling enabled on Ubuntu 12.04 LTS?