VMware vSphere Distributed Switch (VDS) reporting high number of packet drops in inputFilters stats

Products

• VMware NSX

Issue/Introduction

Symptoms:

• vRNI or similar monitoring tools report excess packet drops for VDS port inputFilters stats.
• If VMware NSX is in use, segment statistics illustrate a large number of pack-drops for virtual machine ports. This can occur when no VMs are connected to the segment.
• There is no impact or actual drop observed in the environment.
• Using the VMware Interactive Shell (vsish) from root on the ESXi CLI you witness pktsDropped increasing on the inputFilters: /net/portsets/<SwitchName>/ports/<PortNum>/inputFilters/fc-lookup-input/stats {
• To get SwitchName and PortNum use ESXi CLI commands net-stats -l as root.

[root@esx-01:~] vsish
/> cat /net/portsets/DvsPortset-0/ports/67108886/inputFilters/fc-lookup-input/stats {
   pktsIn:3598
   pktsOut:2157
   pktsDropped:1441        >>>>>>>>>> High number of packets dropped

• Check the above filter over a period of time to validate the pktsDropped counter is increasing while verifying no impact on the VM/port.
• Checking the inputStats we can see it is the same value for dropped packets and filtered packets

[root@esx-01:~] vsish
/> cat /net/portsets/DvsPortset-0/ports/67108886/inputStats
...
FC_INPUT.18504670 <fc-lookup-input:0x0>
   pktsStarted:3598
   pktsPassed:2157
   pktsDropped:0
   pktsFiltered:1441                 >>>>>>>>>> This is the same value as above

Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.

Environment

VMware NSX-T Data Center

Cause

• This is an known issue with the counters and is a false positive.
• This issue can happen in a multi-tier router configuration when using VMware NSX.
• The pktsFiltered counters from inputStats packets are interpreted as pktsDropped in inputFilters.

Resolution

This issue is resolved in VMware ESXi 7.0 Update 3g, available at VMware downloads.