The NSX Manager communicates with NSX Edge through the VIX or Message Bus. It is chosen by the NSX Manager when the Edge is deployed and never changes.
VIX is not supported in NSX 6.3.0 and later.
VIX is used for NSX Edge if the ESXi host is not prepared.
The NSX Manager gets host credentials from the vCenter Server to connect to the ESXi host first.
The NSX Manager uses the Edge credentials to log in to the Edge appliance.
The vmtoolsd process on the Edge handles the VIX communication.
VIX failures occur because of:
The NSX Manager cannot communicate with the vCenter Server.
The NSX Manager cannot communicate with the ESXi hosts.
There are NSX Manager internal issues.
There are Edge internal issues.
Check for VIX errors VIX_E_<error> in the NSX Manager logs to narrow down the cause. Look for errors similar to:
Vix Command 1126400 failed, reason com.vmware.vshield.edge.exception.VixException: vShield Edge:10013:Error code 'VIX_E_FILE_NOT_FOUND' was returned by VIX API.:null Health check failed for edge edge-13 VM vm-5025 reason: com.vmware.vshield.edge.exception.VixException: vShield Edge:10013:Error code 'VIX_E_VM_NOT_RUNNING' was returned by VIX API.:null
In general, if the same failure occurs for many Edges at the same time, the issue is not on the Edge side.