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OpenStack Neutron – Expand and / or update floating IP range

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By Jonas Werner
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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:

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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:

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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:

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[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

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[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

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[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:

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[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)[#
Cloud computing, OpenStack
This post is licensed under CC BY 4.0 by the author.