A subnet is a block of IP addresses and associated configuration state. Subnets are used to allocate IP addresses when new ports are created on a network (OpenStack Docs).
In City Control Panel, the user can fins all subnets listed under Networks > Subnets. In the list, the user can also see which network each subnet is connected to. To view more details about an individual subnet, click the bar for the subnet or click and choose View more as Figure 1 shows. The user can also choose to modify the subnet or to delete it.
Figure 1. Subnets - more details
Some shortcuts are available in each row as well, modify and copy ID, by clicking in the subnet id as shown in the image below (Figure 2).
Figure 2. Shortcuts modify subnet/copy ID
In the same way, by clicking in the network ID, the user can either modify the network the subnet is connected to or copy its ID (Figure 3).
Figure 3. Shortcuts modify network/copy ID
In the top right corner of the page the user can create a new subnet (Figure 4).
Figure 4. Create New Subnet - button
When creating a new subnet, the user should choose name for the subnet, which region the subnet should be created in and create it, a valid CIDR (if no value is specified, a default value will be set automatically for the user). The user can also choose the IP version (IP version 4 or IP version 6, version 4 is the default). The network the subject will be connected to should also be specified by the user (Figure 5).
Figure 5. Create a Subnet