STP

You have connected an endstation directly to the switch and the endstation fails to boot correctly:

The switch has the STP enabled, and the endstation is booting before the STP initialization process is complete. Specify that STP has been disabled for that VLAN, or turn off STP for the switch ports of the endstation and devices to which it is attempting to connect; then, reboot the endstation.

Spanning Tree Domain names:

There are restrictions on STPD names. They cannot contain whitespaces and cannot start with a numeric value.

You cannot add ports within a VLAN to the specified STPD:

Check to ensure that you are adding ports that already exist in the carrier VLAN.

If you see an error similar to the following:

Error: Cannot add VLAN default port 3:5 to STP domain

You might be attempting to add:

Another 802.1D mode STP port to a physical port that already contains an 802.1D mode STP port (only one 802.1D encapsulation STP port can be configured on a particular STP port).
A carrier VLAN port to a different STP domain than the carrier VLAN belongs.
A VLAN and/or port for which the carrier VLAN does not yet belong.

Note

This restriction is only enforced in an active STPD and when you enable STP to make sure you have a legal STP configuration.

Only one carrier VLAN can exist in an STPD:

Only one carrier VLAN can exist in a given STPD although some of the ports on the carrier VLAN can be outside the control of any STPD at the same time.

The StpdID must be identical to the VLANid of the carrier VLAN in that STPD.

The switch keeps aging out endstation entries in the switch FDB:

If the switch continues to age out endstation entries in the switch FDB:

Reduce the number of topology changes by disabling STP on those systems that do not use redundant paths.
Specify that the endstation entries are static or permanent.