OpenStack Neutron – Expand and / or update floating IP range

Sometimes you run out of public IP addresses and need to expand the floating IP range. If a non-interrupted range is available to expand into from the current range simply use:

neutron subnet-update –allocation-pool start=<original-start-ip>,end=<new-end-ip>

This will overwrite the existing range and expand it to the new end-IP.

To add an extra, separate IP range while still keeping the original range, use:

neutron subnet-update <subnet-id> –allocation-pool start=<original-start-ip>,end=<original-end-ip> –allocation-pool start=<additional-start-ip>,end=<additional-end-ip>

Example of extending a continuous IP range:

[root@c6320-n1 ~(keystone_admin)]# neutron subnet-list
+--------------------------------------+--------------+----------------+----------------------------------------------------+
| id                                   | name         | cidr           | allocation_pools                                   |
+--------------------------------------+--------------+----------------+----------------------------------------------------+
| 1b66dad8-2f2c-4667-9460-7729e2a68d1c | sub-pub      | 172.17.4.0/24  | {"start": "172.17.4.130", "end": "172.17.4.199"}   |
| 74c90d00-af79-4f7c-92ef-4e38231e850c | sub_priv2    | 192.168.0.0/24 | {"start": "192.168.0.40", "end": "192.168.0.50"}   |
| e6cb6f7e-5efd-42df-93e6-67ad4b056035 | sub_internal | 192.168.0.0/24 | {"start": "192.168.0.100", "end": "192.168.0.200"} |
| e47c7f4b-85ec-41e4-ad1a-cf9290a97d87 | sub_priv     | 172.16.0.0/24  | {"start": "172.16.0.100", "end": "172.16.0.200"}   |
+--------------------------------------+--------------+----------------+----------------------------------------------------+

View the subnet detail

[root@c6320-n1 ~(keystone_admin)]# neutron subnet-show 1b66dad8-2f2c-4667-9460-7729e2a68d1c
+-------------------+--------------------------------------------------+
| Field | Value |
+-------------------+--------------------------------------------------+
| allocation_pools | {"start": "172.17.4.130", "end": "172.17.4.199"} |
| cidr | 172.17.4.0/24 |
| dns_nameservers | |
| enable_dhcp | False |
| gateway_ip | 172.17.4.1 |
| host_routes | |
| id | 1b66dad8-2f2c-4667-9460-7729e2a68d1c |
| ip_version | 4 |
| ipv6_address_mode | |
| ipv6_ra_mode | |
| name | sub-pub |
| network_id | fa9fb87f-70d9-4e18-83cb-c04695cbed5a |
| subnetpool_id | |
| tenant_id | 8d93e4b0f8454ad7b539d14633d72136 |
+-------------------+--------------------------------------------------+

Update the subnet

[root@c6320-n1 ~(keystone_admin)]# neutron subnet-update 1b66dad8-2f2c-4667-9460-7729e2a68d1c --allocation-pool start=172.17.4.130,end=172.17.4.240
Updated subnet: 1b66dad8-2f2c-4667-9460-7729e2a68d1c
[root@c6320-n1 ~(keystone_admin)]# neutron subnet-show 1b66dad8-2f2c-4667-9460-7729e2a68d1c
+-------------------+--------------------------------------------------+
| Field | Value |
+-------------------+--------------------------------------------------+
| allocation_pools | {"start": "172.17.4.130", "end": "172.17.4.240"} |
| cidr | 172.17.4.0/24 |
| dns_nameservers | |
| enable_dhcp | False |
| gateway_ip | 172.17.4.1 |
| host_routes | |
| id | 1b66dad8-2f2c-4667-9460-7729e2a68d1c |
| ip_version | 4 |
| ipv6_address_mode | |
| ipv6_ra_mode | |
| name | sub-pub |
| network_id | fa9fb87f-70d9-4e18-83cb-c04695cbed5a |
| subnetpool_id | |
| tenant_id | 8d93e4b0f8454ad7b539d14633d72136 |
+-------------------+--------------------------------------------------+
[root@c6320-n1 ~(keystone_admin)]#
[root@c6320-n1 ~(keystone_admin)]#

Example of adding an additional range to an already existing range:

[root@c6320-n1 ~(keystone_admin)]# neutron subnet-update 1b66dad8-2f2c-4667-9460-7729e2a68d1c --allocation-pool start=172.17.4.130,end=172.17.4.199 --allocation-pool start=172.17.4.209,end=172.17.4.240
Updated subnet: 1b66dad8-2f2c-4667-9460-7729e2a68d1c
[root@c6320-n1 ~(keystone_admin)]#
[root@c6320-n1 ~(keystone_admin)]# neutron subnet-show 1b66dad8-2f2c-4667-9460-7729e2a68d1c
+-------------------+--------------------------------------------------+
| Field             | Value                                            |
+-------------------+--------------------------------------------------+
| allocation_pools  | {"start": "172.17.4.130", "end": "172.17.4.199"} |
|                   | {"start": "172.17.4.209", "end": "172.17.4.240"} |
| cidr              | 172.17.4.0/24                                    |
| dns_nameservers   |                                                  |
| enable_dhcp       | False                                            |
| gateway_ip        | 172.17.4.1                                       |
| host_routes       |                                                  |
| id                | 1b66dad8-2f2c-4667-9460-7729e2a68d1c             |
| ip_version        | 4                                                |
| ipv6_address_mode |                                                  |
| ipv6_ra_mode      |                                                  |
| name              | sub-pub                                          |
| network_id        | fa9fb87f-70d9-4e18-83cb-c04695cbed5a             |
| subnetpool_id     |                                                  |
| tenant_id         | 8d93e4b0f8454ad7b539d14633d72136                 |
+-------------------+--------------------------------------------------+
[root@c6320-n1 ~(keystone_admin)]#
[root@c6320-n1 ~(keystone_admin)]#

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