It could be caused if there are too many mac-moves/flaps/loops or new mac learns/moves exceed a certain threshold.

When BCM ASIC learns too many mac-addresses in a short duration, BCM_USD can disable/enable MAC learning in hardware and you can see this message that comes up.

Troubleshoot Layer 2 Switching Issues Topology +-+ Po6 +-+ Understand the Concept of mac-learning on the Switch and NX-OS Configuration Under loop condition, it can happen that the same MAC is learned via two different ports on the switch. You understand the concept of mac learning and how a table is maintained on a switch, when the switch receives a frame, and associates the MAC address of the sender with the LAN port where it was received. End with CNTL/Z.This document describes how to troubleshoot when there is mac move on Nexus 9000 and how to prevent it. The customer is allocated VLAN 10 (outer VLAN tag).Įnter configuration commands, one per line. A Layer 2 protocol tunnel is enabled for STP BPDUs. This example shows a service provider switch that is configured to process Q-in-Q for traffic coming in MAC address learning for Q-in-Q tagged packets is based on the outer VLAN (Service ProviderĬonfiguration Examples for Q-in-Q and Layer 2 Protocol You should only see the outer mac address in your mac address table, Can you post your config? I don't know what u/Daeloan get his information from.

Dynamic mac address learning