BFD tunnels not forming between edge TEPs and Host TEPs

Products

• VMware NSX

Issue/Introduction

• BFD tunnels were not forming between NSX Edge nodes and ESXi hosts. The NSX UI displayed faulty TEP status for the affected Edge transport nodes.
• During verification with the customer, ICMP connectivity between Edge TEPs and host TEPs was confirmed to be functioning as expected; however, no BFD traffic was observed between the nodes.

Environment

• VMware NSX-T environment using a collapsed cluster design
• Edge VM TEP interfaces connected using distributed virtual switch (dVS) port groups
• Edge and ESXi host TEPs configured on the same VLAN
• NSX-T version 3.1.0 or later

Cause

The issue was caused by an unsupported or improper TEP connectivity configuration within the collapsed cluster deployment.

According to the Broadcom KB, Edge TEP and ESXi host TEP interfaces can share the same VLAN only under specific supported configurations, including:

• Edge VM TEP interface connected to a port group on an ESXi host not prepared for NSX
• Edge VM TEP interface connected to a port group on a switch not used by NSX, while residing on an NSX-prepared ESXi host
• Edge VM TEP interface connected to a logical switch on a vDS with NSX-T 3.1.0 or above
• Edge VM TEP interface connected to a logical switch on an NVDS with NSX-T 3.1.0 or above

In this case, the Edge VM was configured using dVS port groups in a collapsed cluster scenario, resulting in BFD tunnel establishment failure despite basic IP connectivity being operational.

Resolution

Reconfigure the Edge VM TEP interfaces to use NSX VLAN segments instead of standard dVS port groups.

This aligns the deployment with supported NSX design guidance and allows proper BFD tunnel establishment between Edge and host TEPs.

Additional consideration:

• The vCenter configuration wizard does not properly account for collapsed cluster deployments and may automatically apply a transport zone that is not visible or available within the NSX UI.
• Manual validation of transport zone assignment and TEP segment configuration is recommended during deployment.

Reference KBs:

• NSX-T Edge TEP networking options