vCenter Server loses management default gateway after reboot in a multi-homed configuration.

Products

• VMware vCenter Server

Issue/Introduction

• Connectivity lost to vCenter Server after rebooting vCenter Server Appliance (VCSA).
• SSH access to the vCenter Server (typically on NIC0) becomes unavailable.
• VCSA is configured with two vNICs and two default gateways:
  This configuration can be confirmed from the vCenter Appliance Managment Interface (VAMI) under Networking:  https://<vCenter Server FQDN>:5480
• vCenter DCUI shows that the VCSA management interfaces default gateway is blank or is set to the default gateway configured for NIC1 in the VAMI.  

Environment

VMware vCenter Server

Cause

This behaviour may be observed when VCSA is configured with two vNICs and two default gateways.  VCSA only supports one default gateway, which resides on the management interface (typically eth0). When a secondary NIC (eth1) is configured with its own gateway, the Photon OS network stack may favor the wrong gateway or lose the management route entirely during the boot sequence, leading to connectivity loss.

The following information is seen beside the NICs default gateway configuration in the VAMI:

"The configuration supports only one default gateway on the vCenter server.  This will replace the existing default gateway and set the one you specify here as the global default gateway."

Resolution

This is a condition that may occur in a VMware vCenter environment.

Workaround

1. Remove default gateway configuration for NIC1 in the VAMI.
2. Reboot VC server.
3. Confirm that default gateway for VC server is the default gateway configured under NIC0 in the VAMI.
   
   NB:  Static routes can be configured to provide more advanced routing options if required.  See the following KB for further details:  Configuring Persistent Static Routes on VCSA
   
   

 

Additional Information

vCenter Server Connectivity Lost to ESXi Hosts and SSH After Adding a New NIC in VAMI