Core issue
The default message is %PM-4-LIMITS:. The number of VLAN port instances on [chars] exceeded the recommended limit of [dec].
This message means that the total number of individual VLAN ports, counted over the module or switch, have exceeded the recommended limit. VLANs can be counted more than once. If VLAN 1 is carried on ten interfaces, it counts as ten VLAN ports. On some platforms, bundling is also ignored for purposes of this count. If eight interfaces on the same module are in one bundle, and the port channel carries VLAN 1, it counts as eight VLAN ports. [chars] is the module name, ffor example, switch or the module number, and [dec] is the recommended limit.
Resolution
Reduce the number of trunks and VLANs configured in the module or switch as recommended in [dec]. Enter the show interfaces trunk privileged EXEC command in order to see the total number of trunks and VLANs.
The maximum logical interfaces for Per VLAN Spanning Tree Plus (PVST+) is 1800 for each module and 13,000 total for the switch. The show spanning-tree summary totals command displays the number of logical interfaces in the STP Active column.
The only way around this is to run Multiple Spanning Tree (MST) versus PVST, which has different limits:
- PVST+ 13,000 total 1,800*/slot
- RPVST+ 10,000 total 1,800*/slot
- MST 50,000 total 6,000*/slot
Otherwise, pruning unnecessary VLANs from trunks is the best way to reduce the number of logical interfaces on a module or switch. But, regardless of STP mode, 10 Mbps, 10/100 Mbps, and 100 Mbps switching modules support a maximum of 1,200 logical interfaces per module.
Refer to the Understanding VTP Pruning section of Configuring VLAN Trunking Protocol (VTP) for more information.
Error message
%PM-SP-4-LIMITS
