NSX Edge TEP tunnels show as DOWN when bridging is enabled

Products

• VMware NSX

Issue/Introduction

• ESXi host prepared for NSX-T and the host TEPs use the same IP range/subnet as the Edges.
• Tunnels between NSX-T Edge and ESXi nodes displays as Down even when there are no connectivity issues.
• Edges are being used for bridging.
• If bridging is NOT used, please see KB 321171- Tunnels between NSX-T Edge nodes and ESXi nodes show as down even when there are no connectivity issues.

Environment

• VMware NSX-T 3.x
• VMware NSX 4.x

Cause

This issue occurs when ESXi compute transport nodes TEPs and Edge VMs are in the same subnet.

For tunnels between an Edge VM and its outer ESX compute transport nodes, BFD packets sent from the ESXi node will be delivered to the Edge VM without encapsulation, and the Edge VM drops the BFD packets without encapsulation.

For tunnels between an Edge VM and an ESX node which is not the host of certain Edge VM, BFD packets sent from the ESXi node is dropped by the ESXi node hosting the Edge VM because these packets are not destined to the local TEPs of the ESXi node hosting the Edge VM.

Resolution

When bridging is used, the ESXi TEPs must use a separate IP range/subnet from the NSX Edge nodes.

Please see KB 317168 - NSX-T Edge TEP networking options and page 325 of the NSX design guide for further details.