I am following the openstack installation guide for redhat. I am trying to configure networking in compute node. I have installed all the necessary packages. On controller node when I issue the following command, it is throwing an error.

nova network-create vmnet --fixed-range-v4=20.0.0.14/24 --bridge-interface=br100 --multi-host=T

ERROR: The server has either erred or is incapable of performing the requested operation. (HTTP 500) (Request-ID: req-9c5d0e39-e4ae-4024-bbc4-2c5ffd4aa540)

I have three NIC cards for controller and compute. eth0, eth1 and eth2. etho is public netwrok, rest are data and internal networks. What IP range has to be mentioned in the vmnet above ?