[VMCS] vCenter Connectivity Issues in a SDDC Group with External VPCs

Products

• VMware

Issue/Introduction

To provide troubleshooting steps that can be taken to review the SDDC Group networking configuration when vCenter connectivity issues are experienced. These vCenter connectivity issues impact the ability to manage the SDDC environment via the vShpere Client.

Symptoms:

• A SDDC group is configured with external VPCs.
• No network access to the vCenter from VMs within the SDDC.
• vCenter, ESXi hosts, and VMs are up and running.
• vSphere Client is inaccessible.
• The Networking and Security tab within the VMC does not load.

Cause

The network configuration within an External VPC was modified, a /32 route was statically set in a vTGW which overlapped with one of the SDDC's vCenter IPs. Any traffic aimed at reaching the vCenter IP was forced to route over to that External VPC as the /32 is the most specific route that exists in networking.

Resolution

Changing the network configuration so that the overlapping  /32 route was removed from the external VPC resolved the connectivity issues.