Skyline health intermittently reports RDMA configuration issues, when RDMA is enabled for vSAN network.

Products

• VMware vSAN

Issue/Introduction

In vCenter UI, Skyline health reports below warnings with PFC (Priority flap control) getting flapped intermittently.

vsish shows the DCB is enabled and PFC shows disabled.

# vsish
/net/pNics/vmnic3/dcbx/> get dcbEnabled
DCB state and version {
   Is DCB Enabled:1       <----- DCB enabled.
   Major version of DCB:0x02
   Minor version of DCB:0x00

/net/pNics/vmnic3/dcbx/> get capabilities
DCB Capabilities {
   Priority Groups:1
   Priority Flow Control:0    <----- PFC disabled.
   User Priority to Traffic Class Mapping:0
   Number of PG Traffic Classes supported:0x03
   Number of PFC Traffic Classes supported:0x03

vmnic1 and vmnic3 configured for vSAN reporting PFC not enabled and skyline health reports alarms has PFC not enabled intermittently.

2026-03-05T08:45:11.802Z In(14) vsand[2102875]: [opID=agw-0000975-438b-117b VsanEsxHclUtil::GetPnicFromHostNetInfo] Get vsan vmknic-pnic mapping {'vmk2': ['vmnic1', 'vmnic3']}
2026-03-05T08:45:11.802Z In(14) vsand[2102875]: [opID=agw-0000975-438b-117b VsanEsxHclUtil::_GetListOfRoceV2CapableDevices] roceV2 capable devices from NetworkSystem: ['vmnic2', 'vmnic3', 'vmnic0', 'vmnic1']
2026-03-05T08:45:11.802Z In(14) vsand[2102875]: [opID=agw-0000975-438b-117b VsanEsxHclUtil::_PopulatePnicDcbConfig] Get dcb config mode: IEEE,pfc:None
2026-03-05T08:45:11.803Z In(14) vsand[2102875]: [opID=agw-0000975-438b-117b VsanEsxHclUtil::_PopulatePnicDcbConfig] Get dcb config mode: IEEE,pfc:3

Environment

VMware vSAN 9.x

Cause

This can cause due to the configuration issue with the RDMA.

Resolution

Need to set the below setting to use RDMA NICs.
1. On ESXi vSAN VDS, set LLDP as "Listen".
2. On Cisco switch, enable LLDP.
3. On NIC in BIOS setup, enable DCB and LLDP.