Intermittent Connectivity Issues to Virtual Machines in Cisco ACI Environments

Products

• VMware vCenter Server
• VMware vSphere ESXi
• VMware vSphere ESX 8.x

Issue/Introduction

• Virtual Machines (VMs) experience intermittent ICMP/network drops
• Cisco ACI Fabric reports "Rogue Endpoint" or MAC flapping alerts between different leaf switches for VM MAC addresses
• vSphere environment shows no evidence of VM migrations, port flaps, or high resource contention at the time of the drops
• Workload (high or low) has no effect on when the symptom is experienced

Environment

• VMware ESX
• VMware vSphere 8.0 / vCenter Server
• Cisco ACI Fabric

Cause

Multicast traffic generated outside the vSphere environment using the MAC addresses of the affected virtual machines triggers the Cisco ACI fabric's IP/MAC binding algorithms, resulting in the MAC being detected as flapping and shut down by rogue endpoint protections.

Resolution

Engage Cisco for support regarding ACI "IP Data-Plane Learning" and "L2 Unknown Unicast" settings.

Additional Information

Cisco ACI Endpoint Learning White Paper

Cisco APIC Basic configuration Guide: Bridge Domains