Networks created within the openstack platforms are not routed trough NTNU, thus in theory it is not important which subnet is selected. It might however be a problem if your virtual machine needs to contact external resources and you have provision your virtual machines within the same address range that is currently being use elsewhere, causing your local address range to overlap with the address range of another network. Because of this, it is common practice to use the address ranges specified in the RFC1918 (a.k.a IPv4 Private Address Space):
- 10.0.0.0/8
- 172.16.0.0/12
- 192.168.0.0/16
RFC1918 within NTNU
NTNU is however using the following subnets within the RFC1918 range, therefore their use should be avoided:
10.0.0.0/8 - Large pieces of this range is already in use; and this block is likely to be used in new subnets within NTNU as well. The general purpose floatin-IP's assigned in openstack is also from this range, and it can thus involve a bit of confusion if both the vm's IP and the floating-ip looks the same. It is thus recommended not to use this block at all.
172.16.0.0/16 - Previously used as floating-IP's in skyhigh.hig.no; free in other clouds
172.17.0.0/16 - Used within NTNU in Gjøvik, and is thus not recommended to use it in openstack networks.
- 192.168.0.0 - The following twelve subnets are partly used in NTNU Ålesund, the rest are free:
192.168.10.0/24
- 192.168.30.0/24
- 192.168.50.0/24
- 192.168.90.0/24
- 192.168.110.0/24
- 192.168.114.0/24
- 192.168.201.0/24
- 192.168.212.0/24
- 192.168.221.0/24
- 192.168.222.0/24
- 192.168.223.0/24
- 192.168.224.0/24