VM-to-VM Packet Loss After Edge Bridge Configuration / error "Edge Transport Node detects looped MAC address ##:##:##:##:##:## from bridge port"

Products

• VMware NSX

Issue/Introduction

This article explains how to prevent an L2 loop, which occurs when an Edge Transport Node detects a looped MAC address from a bridge port.

Edge Syslog:
202#-0#-18T00:23:25.930Z t-edge.###.#####.### NSX 10373 SWITCHING [nsx@6876 comp="nsx-edge" subcomp="datapathd" s2comp="lswitch" tname="dp-learning4" level="WARN"] Edge Transport Node ######-####-#####-####-########## detects looped MAC address ##:##:##:##:##:## from bridge port ######-####-#####-####-##########
######-####-#####-####-########## no longer detects looped MAC address from bridge port after 15#####53 seconds.0000####0-######-####-#####-####-##########.

Environment

VMware NSX-T Data Center

Cause

With MAC Learning, forged transmit, Mac change and promiscuous mode enabled, the underlying vSphere Distributed Switch (VDS) learn the MAC addresses of the VMs that exist on the NSX overlay side of the bridge. As a result, when traffic from the physical network was destined for these VMs, the VDS would flood the packet to all its ports. The NSX Edge bridge correctly identified this flooded traffic returning to it as a network loop and dropped the packet as a protective measure, causing the connectivity failure.

Resolution

The recommended solution was to enable MAC learning feature and disable forged transmit and promiscuous mode. specific vSphere Distributed Port Group that the NSX Edge VM's bridging interface is connected to.

Additional Information

Reference document Configure an Edge VM for Bridging

Configure an Edge VM for Bridging

NSX Edge Bridge and Promiscuous Mode: Avoiding a Common Error