Changing the IP address subnet for the VCF Fleet's VCF Management Network on a fresh VCF 9.1 deployment

Products

• VCF Operations
• VMware SDDC Manager / VCF Installer

Issue/Introduction

A fresh VCF Fleet for a new datacenter has been deployed. Currently we have the fleet network on a ##.##.##.##/26 network with a gateway on .#. The bottom half of the subnet has been reserved for the VCF Fleet management services based on the 30 IP address minimum recommendation.

However, before finishing the HA VCF services runtime nodes and components, the range is nearly fully utilized. It would be desirable to convert to a ##.##.##.##/25 subnet on the network side since the VCF Fleet has already been deployed. Everything would stay the same except the subnet mask.

Is it possible to change just the subnet mask for the VCF Management Network without disrupting the Fleet Management Services?

Environment

VMware Cloud Foundation 9.1

Resolution

There is not a supported way to change the IP range and subnet mask for the VCF Management Network after deployment.

The recommendation for a fresh deployment is to redeploy with the currently desired subnet and subnet mask defined in the installation from the beginning.

Additional Information

• For more information on IP requirements for VCF 9.1, see vSphere Foundation FQDNs and IP Addresses.
• If the VCF Management Network subnet is already large enough and there is only a need to expand the VCF Services Runtime IP pool, there are options to expand via Network Actions for VCF Services Runtime. 
• If redeployment is not an option and there is a lack of available IPs on the VCF Management Network, see KB 440223: "Not all addresses from the VCF Management Services IPv4 pool are part of the management network" when deploying VCF Management Services. This KB outlines an API method to define a custom network for the VCF Management Services as an alternative to expanding the VCF Management Network's subnet.
• A Feature Request for Day-N action to change subnet of VCF Management Network has been filed.  Please vote on the feature request if interested in this functionality.