BGP Peering Failure between NSX Edges and Arista Switches on HP Synergy

Products

• VMware NSX

Issue/Introduction

This article addresses a BGP peering failure where neighborship cannot be established between VMware NSX Edge nodes and Top of Rack (Arista) switches.

• Symptoms:

  • BGP neighborship status remains in a "Down" or "Idle" state.

  • Bi-directional packet captures at the ESXi host uplink (vmnic) show ARP requests leaving the Edge node but no ARP replies returning from the physical network.

  • Total loss of Layer 2 reachability between the Edge TEP/Uplink interfaces and the physical switch IPs.

Environment

• Primary Product: VMware NSX 4.x / 9.x (Validated on 9.0.1.0)

• Hardware Fabric: HPE Synergy with OneView management.

• Physical Switching: Arista Top of Rack (ToR) switches.

• Connectivity Path: NSX Edge -> ESXi Host -> HPE Synergy Fabric Interconnect -> Arista ToR Switches.

Cause

The failure is caused by a missing VLAN configuration within the HPE Synergy (OneView) chassis. Specifically, the required BGP peering VLANs were not defined in the Ethernet Network settings or added to the Network Set associated with the Arista physical uplinks. Because the HPE Synergy fabric interconnect acts as an intermediate Layer 2 boundary, it drops tagged traffic for any VLANs not explicitly permitted in its configuration, preventing ARP resolution and subsequent BGP establishment.

Resolution

To resolve this issue, the missing VLANs must be defined and permitted within the HPE Synergy management console.

1. Prerequisites:

   • Identify the specific VLAN IDs used for NSX Edge BGP peering.

   • Ensure you have administrative access to the HPE Synergy OneView console.

2. Log in to the HPE Synergy OneView console.

3. Create new Ethernet networks for the missing VLANs.

   • Ethernet networks 

4. Navigate to Networking > Network Sets.

   • Edit a network set 

5. Verify that the changes are applied to the Logical Interconnects.

6. Verification:

   • Perform a packet capture on the NSX Edge or ESXi host uplink to confirm ARP replies are now being received.

   • Check the BGP neighbor status in the NSX Manager UI

   • Confirm the state transitions to Established.

Additional Information

• Troubleshooting NSX BGP