ESXi vmkwarning log is filled with Flow Cache warnings related to TTL

Products

• VMware NSX

Issue/Introduction

• ESXi host logs are flooded with log entries similar to the below:
  /var/run/log/vmkwarning.log
  

  <Timestamp> Wa(180) vmkwarning: cpu64:2098149)WARNING: FlowCache.fc: FC_ActionVDR:1419: [nsx@6876 comp="nsx-esx" errorCode="ESX6"]TTL 1 is not greater than VDR action data hops 1

• There is no dataplane traffic impact observed for the VM traffic hosted on the ESXi host.

Environment

VMware NSX

Cause

Decrementing TTL is expected logic in Layer 3 networking.  When TTL is decremented to zero for a packet, then that packet gets dropped.  Applications can also purposefully set packets with a low TTL value.

Resolution

This issue is resolved in VMware NSX 4.1.1, available at Broadcom downloads.

If you are having difficulty finding and downloading software, please review the Download Broadcom products and software KB.

 

NB:  From NSX 4.1.1, the process is optimized by replacing these logs with counters on flow-cache stats which can be obsevred with the following host command:
        nsxdp-cli fc stats get