Cannot ping the ESG's internal interface from a VM connected to a logical switch across a DLR on NSX for vSphere

Products

• VMware NSX

Issue/Introduction

Symptoms:

Based on the diagram above, lets assume you have:

• VM1 connected to VNI 5000
• Transit VNI 5001 between the DLR and ESG

You can ping the DLR lif which is the default gateway for VM1.

However, when you try to ping the internal interface of the ESG from VM1, it is unsuccessful unless the ESG is on the same ESXi host as VM1.

Environment

VMware NSX for vSphere 6.2.x
VMware NSX for vSphere 6.3.x
VMware NSX for vSphere 6.4.x

Resolution

This happens if the VLAN which is used by VXLAN (check the logical network preparation tab under Installation) as shown below isn't trunked through all the uplinks on both ESXi hosts or isn't stretched across the physical network end-to-end between them:

To resolve this issue:

Ensure that the physical network between these two ESXi hosts (one on which the VM resides and the other on which the ESG resides, have that VLAN (110 in the example above) configured end to end on all the uplinks used by the ESXi host for the VXLAN-prepared DVSwitch .