North-South Traffic Fails Reaching Tier-0 Router Due to ARP Failure on Edge Node

Products

• VMware NSX

Issue/Introduction

• North-South traffic from VMs on NSX logical segments is failing to reach the Tier-0 (T0) router.
• Traceflow analysis indicates that packets are "Dropped due to ARP failure" before reaching the transit-bp interface on the NSX Edge node.

Environment

VMware NSX

Resolution

To isolate the specific cause of the ARP failure, proceed with the following validations:

1. VLAN Tagging : Verify that the transport VLAN tagging configured on the logical segments attached to the Edge nodes matches the upstream physical switch port configurations.
2. Edge pNIC Link State : Validate the operational state of the Edge physical NIC (pNIC) bond to ensure the link state is 'UP'.
3. Tier-0 HA Configuration : Verify the High Availability (HA) configuration is present, active, and fully synchronized on the Tier-0 gateway.
4. Transport Node Health : Validate the Host Transport Node reports a 'Success' configuration state and is not marked as 'Degraded' within the NSX Manager UI.
5. Upstream ARP Resolution : Confirm the receipt of ARP replies from the upstream physical network infrastructure by executing a packet capture on the Edge transit interface.