Tunnels between NSX-T Edge and ESXi nodes displays as Down even when there are no connectivity issues

Products

• VMware NSX

Issue/Introduction

• Edge virtual machines reside in the ESXi host prepared for NSX-T as well as compute workloads being on the same host switch
• Tunnels between NSX-T Edge and ESXi nodes displays as Down even when there are no connectivity issues.
• If the edges are being used for bridging, please see KB 414269 - NSX TEP tunnels show as DOWN when bridging is enabled.

Environment

• VMware NSX-T Data Center 3.x
• VMware NSX 4.x

Cause

This issue occurs because the TEPs of the ESXi compute transport nodes 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

To resolve this issue, you need to move the Edge node uplinks to a NSX backed VLAN trunk port group, or you can move the Edge TEPs to use a different subnet/VLAN than the TEPs in the ESXi compute transport nodes.  The solution depends on your deployment requirements.

For more information, please see KB 317168 - NSX-T Edge TEP networking options.

 

 

Additional Information