VMware NSX Transport Node Tunnels Intermittently Flap Due to External DNS Flooding and High Host Latency

Products

• VMware NSX

Issue/Introduction

VMware NSX Transport Node tunnels intermittently and randomly go up and down, which causes the corresponding ESXi hosts to report a degraded status in the NSX UI.

Environment

VMware NSX

Cause

The underlying cause was an external network issue impacting DNS availability and creating high latency on the ESXi host running the DNS Virtual Machine (VM).

A field appliance was creating a DNS flooding event targeting the primary DNS server, which caused high latency on the ESXi host where that DNS VM was running.

Resolution

The issue is resolved by addressing the external network issue and performing recommended system and driver upgrades.

• Stop the DNS Flooding Source: Isolate or disconnect the field appliance identified as creating the DNS flooding event targeting the DNS server.

Workaround.

• Move the DNS VM into the firewall exclusion list, for the host to begin reporting a healthy, non-degraded status.

Additional Information

For additional troubleshooting refer to the master article for NSX Troubleshooting.

• Troubleshooting NSX issues