We’re excited to announce the immediate availability of the modifiable virtual cloud network (VCN), Subnet, and VLAN classless inter-domain routing (CIDR) feature in Oracle Cloud Infrastructure (OCI). This feature allows you to dynamically change the size of your VCN by adding or resizing existing CIDR ranges. You can also resize subnets VLANs by adjusting the subnet mask.
A modifiable VCN is a VCN that can be adjusted in size by removing, adding, or resizing existing VCNs to avoid migration efforts.
For example, if your VCN was created with the CIDR range 10.0.0.0/16, you can add another CIDR of 10.1.0.0/16. You can also change the size of the existing 10.0.0.0/16 to 10.0.0.0/24 or other CIDR ranges.
Figure 1: Adding a CIDR to an existing VCN
A modifiable subnet or VLAN is a subnet that you can change in size to allow a smaller or large IP space.
For example, 10.0.0.0/24 can become 10.0.0.0/22 without having to rebuild or manually migrate your subnet or VLAN.
Figure 2: Shrinking the CIDR of an existing subnet
This flexibility allows you to perform the following new tasks:
Add extra IP address space to a VCN to allow space for more subnets to more resources without the need to peer with a newly created VCN.
Reclaim unused IP addresses that are needed elsewhere in your environment.
Resize VCNs to reduce the number of resources that are allowed in a particular VCN.
Change the netmask to reduce or increase the size of a subnet or VLAN CIDR.