NSX VTEP tunnels show Down when using VLAN 0 (Default VLAN)
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NSX VTEP tunnels show Down when using VLAN 0 (Default VLAN)

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Article ID: 445819

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Updated On:

Products

VMware NSX

Issue/Introduction

NSX Transport Nodes fail to establish VTEP tunnels (BFD Down). vmkping tests between VTEP IPs fail despite the hosts being in the same broadcast domain.

Cause

Many physical switches do not forward or correctly tag Geneve/BFD packets when the VTEP VLAN is set to 0 (native/untagged) on a trunk port, leading to packet drops.

Resolution

  1. Identify a valid VLAN ID for overlay traffic (e.g., VLAN 100).
  2. Ensure this VLAN is configured and allowed on physical switch ports connected to the ESXi hosts.
  3. Modify the Uplink Profile in NSX Manager:
    • Navigate to System > Fabric > Profiles > Uplink Profiles.
    • Edit the profile used by the transport nodes.
    • Change the Transport VLAN from 0 to the assigned VLAN ID.
  4. Verify connectivity using vmkping -I vmkX ++netstack=vxlan [Remote_VTEP_IP].
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