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Single public IP address (/32) as Floating IP

asked 2019-04-14 07:25:50 -0500

niiku gravatar image

I have a single server where I installed OpenStack using Packstack. My server provider allows me to add individual IP addresses to the server, but these are usually in a different subnet than the server IP. I can add this additional IP to the bridge (e.g. br-ex with ip addr add), which is then also available.

Is it possible to add single public IP addresses (/32) as floating IPs to a VM without having a subnet (e.g. /29)? Or is it mandatory that I place a router between a private subnet (e.g. and a public subnet, so that a /29 is the minimum?

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When I create a /32 subnet with neutron, I can't use it for floating IP, as I would also need a router to connect it to a private network. I simply want to create a NAT between the public IP and private IP, but possible without a router...

niiku gravatar imageniiku ( 2019-04-14 07:38:19 -0500 )edit

To associate a floating IP with an instance, as far as I know the instance must be connected to a tenant network that is routed to the floating IP’s external network. I currently don’t find the corresponding documentation.

Bernd Bausch gravatar imageBernd Bausch ( 2019-04-14 08:54:57 -0500 )edit

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answered 2019-04-14 07:34:02 -0500

updated 2019-04-14 07:45:45 -0500

A floating IP must come from an external network. Now, this network may have several subnets, and you can specify the subnet from which the floating IP will be allocated. Perhaps it's possible to create /32 subnets. Alternatively, admins can specify the IP address when creating a floating IP.

Further reading: The floating IP create API.

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Asked: 2019-04-14 05:57:37 -0500

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Last updated: Apr 14