vmnic link down for few seconds

Products

• VMware vSphere ESXi

Issue/Introduction

vmnic using nmlx5-core link down for few seconds.

Log indicates that its driver detected link down/up.

YYYY-MM-DDThh:mm:ss.###Z cpu0:2098185)netschedHClk: NetSchedHClkNotify:4662: vmnic5: link down notification
YYYY-MM-DDThh:mm:ss.###Z cpu0:2098185)<NMLX_INF> nmlx5_core: vmnic5: nmlx5_en_UplinkLinkStateSetOS - (nmlx5_core_en_uplink.c:5065) Changing link status from UP Full Duplex 25000 to DOWN Half Duplex 0
YYYY-MM-DDThh:mm:ss.###Z cpu0:2098185)<NMLX_INF> nmlx5_core: vmnic5: nmlx5_en_UpdatePhyData - (nmlx5_core_en_main.c:1038) called
YYYY-MM-DDThh:mm:ss.###Z cpu0:2098185)netschedHClk: NetSchedHClkNotify:4654: vmnic5: link up notification
YYYY-MM-DDThh:mm:ss.###Z cpu0:2098185)<NMLX_INF> nmlx5_core: vmnic5: nmlx5_en_UplinkLinkStateSetOS - (nmlx5_core_en_uplink.c:5065) Changing link status from DOWN Half Duplex 0 to UP Full Duplex 25000
YYYY-MM-DDThh:mm:ss.###Z cpu0:2098185)<NMLX_INF> nmlx5_core: vmnic5: nmlx5_en_UpdatePhyData - (nmlx5_core_en_main.c:1038) called

Environment

VMware ESX
VMware ESXi

Cause

The log means nmlx5 driver simply detected link down/up. Drivers usually detect link state based on hw register value, so we recommend engaging hardware/network vendor to look into this.

Resolution

Usually it's not a software issue, so we'd recommend engaging hardware/network vendor to investigate.

Additional Information

Japanese KB: vmnic のリンクが数秒間ダウンする