In OpenStack Neutron, many times one prefers to rely on DHCP to have instances (VMs) have IP addresses assigned, mostly for simplicity. But there are cases where one would like to reserve a few IPs statically to be used by certain VMs. Well, it is possible to achieve this by manually creating ports inside the tenant network and attach them to an instance.
For example:
$ neutron net-list
+--------------------------------------+---------+--------------------------------------------------+
| id | name | subnets |
+--------------------------------------+---------+--------------------------------------------------+
| 3d1b9e2c-485c-42dd-bc81-acc1f901e8fc | private | 5e2fa420-b780-4f44-90e7-8dad7a299f73 10.0.0.0/24 |
| 5b078cbb-ffc8-40a4-a3d0-d129c91eeba2 | public | 5f09a031-fa5d-4c80-884d-8a7cf82977c9 |
+--------------------------------------+---------+--------------------------------------------------+
$ neutron net-show private
+-----------------+--------------------------------------+
| Field | Value |
+-----------------+--------------------------------------+
| admin_state_up | True |
| id | 3d1b9e2c-485c-42dd-bc81-acc1f901e8fc |
| name | private |
| router:external | False |
| shared | False |
| status | ACTIVE |
| subnets | 5e2fa420-b780-4f44-90e7-8dad7a299f73 |
| tenant_id | c38cd73e1e8e41d880001e621aa3ef3d |
+-----------------+--------------------------------------+
$ neutron subnet-show 5e2fa420-b780-4f44-90e7-8dad7a299f73
+------------------+--------------------------------------------+
| Field | Value |
+------------------+--------------------------------------------+
| allocation_pools | {"start": "10.0.0.2", "end": "10.0.0.254"} |
| cidr | 10.0.0.0/24 |
| dns_nameservers | 8.8.4.4 |
| | 8.8.8.8 |
| enable_dhcp | True |
| gateway_ip | 10.0.0.1 |
| host_routes | |
| id | 5e2fa420-b780-4f44-90e7-8dad7a299f73 |
| ip_version | 4 |
| name | private_subnet |
| network_id | 3d1b9e2c-485c-42dd-bc81-acc1f901e8fc |
| tenant_id | c38cd73e1e8e41d880001e621aa3ef3d |
+------------------+--------------------------------------------+
This tenant subnet is using CIDR 10.0.0.0/24. Let’s say we want to reserve IP address 10.0.0.200. A possible solution when using OpenStack Neutron consists of manually creating a port that reserves that address:
$ neutron port-create private --fixed-ip ip_address=10.0.0.200 --name win1
Created a new port:
+-----------------------+-----------------------------------------------------------------------------------+
| Field | Value |
+-----------------------+-----------------------------------------------------------------------------------+
| admin_state_up | True |
| allowed_address_pairs | |
| device_id | |
| device_owner | |
| fixed_ips | {"subnet_id": "5e2fa420-b780-4f44-90e7-8dad7a299f73", "ip_address": "10.0.0.200"} |
| id | 74a86226-c286-4395-a223-a9fc3728e5b9 |
| mac_address | fa:16:3e:05:b2:8d |
| name | win1 |
| network_id | 3d1b9e2c-485c-42dd-bc81-acc1f901e8fc |
| security_groups | 1a02d4ff-99eb-4f69-ba18-22141e7ba2b9 |
| status | DOWN |
| tenant_id | c38cd73e1e8e41d880001e621aa3ef3d |
+-----------------------+-----------------------------------------------------------------------------------+
Once this is done, it is possible to boot a new Nova instance (VM) attached to this particular port:
$ nova boot --flavor=m1.small --image=w2012r2 --nic port-id=74a86226-c286-4395-a223-a9fc3728e5b9 win1
The nice thing about using this port is that the instance is able to get the 10.0.0.200 IPv4 address either by relying on DHCP, or just by having this IPv4 address configured statically 🙂
felipe-alfaro.com 
Hello, I enjoy reading through your article.
I wanted to write a little comment to support you.
Good day! This is kind of off topic but I need some guidance
from an established blog. Is it very hard to set up your own blog?
I’m not very techincal but I can figure things out pretty fast.
I’m thinking about making my own but I’m not sure where to begin. Do you have any ideas or suggestions?
Many thanks
Pingback: styk.tv | fixed ip addresses with openstack neutron for tenant networks
Hello my friend! I want to say that this article is awesome, nice written and include almost
all vital infos. I would like to peer more posts like this .
What’s Going down i am new to this, I stumbled upon this I
have discovered It positively helpful and it has helped me out loads.
I hope to contribute & help different users like
its aided me. Good job.
There’s certainly a great deal to know about
this issue. I like all of the points you have made.
I read this piece of writing completely regarding
the difference of most up-to-date and earlier technologies, it’s remarkable article.
Yesterday, while I was at work, my cousin stole my apple ipad and tested to see if it can survive a twenty five
foot drop, just so she can be a youtube sensation. My iPad is now
broken and she has 83 views. I know this is completely off topic but I had to share it with
someone!
Wonderful goods from you, man. I have understand your stuff previous to and
you’re just too magnificent. I really like what you have acquired here, really like what you are saying and the way
in which you say it. You make it entertaining and you still care for to keep it sensible.
I can not wait to read far more from you. This is really a terrific site.
Very descriptive article, I liked that a lot. Will there be a part 2?