Multi-Homing NICs is not supported for Management Tagged Interfaces or vCenter High Availability

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

• vCenter Server Appliances supports Multi-Homing NICs except for management tagged interfaces with HA enabled.
• vCenter Server Appliance supports up to 4 NICs, prior versions of the vCenter Server supported only a single NIC.
• When the vCenter Server Appliance configured with multiple NICs and HA is enabled, only the first NIC (eth0) is managed by vCenter High Availability, the other NICs will be copied with identical configuration to the Passive and Witness Nodes, resulting in duplicate IPs.
• When multi-homed kernel interfaces are tagged with the management flag vsphere cluster HA will not be able to definitively tigger and HA event.
  • The management tag's purpose is for vSphere Cluster HA to be able to detect when a host is management network isolated.
  • There are two elements needed for cluster HA to trigger the HA event.  The presence of datastore heartbeats and keep alives to the kernel interface of the host determine when to trigger an HA event.
    When both are detected as not present an HA event is declared. Virtual machines are relocated to other hosts per their HA settings.
  • If there are two Kernel ports tagged with the management flag it is possible to have a true HA event occurring, and cluster HA could miss read this since one of the interfaces flagged for management is still reachable.
• The absolute state for an HA event is both management networking is not present and the host is not heartbeating with storage. 

Environment

• VMware vCenter Server 8.0
• VMware vCenter Server 7.0.x
• VMware vSphere 8.0.x
• VMware vSphere 7.0.x

Resolution

• Do not use Multiple NICs on a vCSA with vCenter Server High Availability.
• Do not  tag multiple kernel ports of an ESXi server with the management flag.