NSX TEP Tunnels Down on HPE Synergy 6310C Adapters

Products

• VMware NSX

Issue/Introduction

On a newly deployed NSX cluster, TEP (Tunnel Endpoint) tunnels fail to establish or remain in an intermittent state. This causes a loss of overlay network connectivity, preventing VMs on NSX segments from communicating externally. Specifically:

• BFD sessions show as Down.
• Connectivity tests (vmkping) between TEP interfaces fail.
• Moving a VM to a different host results in a total loss of connectivity.

Environment

• VCF 5.2.2
• vCenter 8.0 Update 3h
• HPE Synergy 6310C 25/50Gb Ethernet Adapters
• VMware NSX

Cause

This issue is caused by a hardware-level misconfiguration in the HPE Synergy 6310C adapter BIOS. If Virtual Ethernet Bridge (VEB) mode is disabled, the adapter cannot facilitate the internal virtual function communication required for NSX TEP encapsulation traffic. Packet captures confirm that BFD State Init packets are transmitted but never received by the peer host, indicating they are dropped at the physical hardware layer

Resolution

Modify the hardware configuration in the host BIOS to enable VEB mode.

1. Reboot the affected ESXi host and enter the System Utilities (BIOS).
2. Navigate to the settings for the HPE Synergy 6310C 25/50Gb Ethernet Adapter.
3. Locate the Virtual Ethernet Bridge (VEB) mode setting.
4. Change the setting to Enabled.
5. Save changes and exit to reboot the host.

Verification: After the reboot, verify that BFD sessions have transitioned to the Up state by running the following command on the ESXi host CLI: nsxdp-cli bfd sessions list