Hello @Robert Plunkett
A MACFLAP error occurs in network switches when the same MAC address is detected on different switch ports rapidly and repeatedly. This situation leads to the MAC address table being updated frequently, causing instability in the network as the switch attempts to keep track of the device's correct location. MAC flapping is often indicative of network issues like a Layer 2 loop, where packets circulate endlessly in the network due to redundant paths without proper loop prevention mechanisms, such as the Spanning tree Protocol. This looping traffic can cause the switch to see the MAC address on multiple interfaces almost simultaneously.
Another common cause of MACFLAP errors is the misconfiguration of port channels or link aggregation groups. If interfaces are not consistently configured as part of the port channel on both the switch and the connected device, traffic may appear to come from different member interfaces, leading to MAC address flapping. Additionally, faulty network devices or incorrect switch configurations, such as duplicate MAC addresses on different devices, can contribute to the problem. Virtualization environments, where virtual machines migrate across hosts, can also trigger MACFLAP events if the switches are not configured to handle such mobility properly.
To resolve MACFLAP issues, it is essential to first identify the root cause. If a L2 loop is suspected, ensure that loop prevention protocols like STP are correctly configured and functioning. For port channel misconfigurations, verify that both ends of the connection are consistently set up for link aggregation. In cases of device misbehavior or duplicate MAC addresses, investigating and fixing the problematic devices can help. Finally, for virtualized environments, configuring the switches to recognize and adapt to virtual machine mobility can mitigate the issue.
Best regards
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