Applied patch from below link in order to add ethernet network type support to LXC.

Launching LXC based VM using openstack Icehouse release which uses libvirt in background fails with below error:

LOG shows "error : virNetDevVethCreate:196 : internal error: Failed to allocate free veth pair after 10 attempts" and also gives ret == -1 for virNetDevVethCreate which depicts that "virNetDevVethCreate" failed.

But by defining XML file manually using virsh utility I am able to launch LXC based VM successfully with network type Ethernet. 

Please help as I am quite new to this virtualization world. Its urgent any help/pointers are welcome.

Thanks

Pradeep Kumar