LLDP traffic is not being forwarded between two virtual machines.

Products

• VMware Cloud Foundation
• VMware vSphere ESXi 8.0

Issue/Introduction

LLDP traffic is not observed between two virtual machines, even if on the same ESXi host.

Environment

ESXi 8.x
VCF 9.0

Cause

LLDP frames are filtered by default with the BPDU filter NetMisc_DropBPDUPackets at the virtual switch.

Resolution

Disable Net.BlockGuestBPDU as per BPDU Filter feature in vSphere: 

1. Using the vSphere Client, switch to the Hosts and Clusters view.
2. Click the desired host from the inventory tree view in the left pane.
3. Click the Configuration Tab and then Advanced Settings under Software.
4. Click Net and then locate the Net.BlockGuestBPDU option.
5. Change the value to 0, which disables BPDU filtering.
6. Click OK.

 

Note: By disabling BPDU filtering you are allowing all virtual machine vNIC's on the ESXi host to send not only LLDP but also other BPDU's. 

Additional Information

Understanding the BPDU Filter feature in vSphere

Troubleshooting Denial of Service attack in virtual infrastructure cluster

Configuring advanced options for ESXi

Deploying a virtual APIC Using VMware vCenter