Spanning tree protocol I have a questions regarding STP and i would like to know if STP is only a feature of layer 2 switches? i am on GNS3 and i am trying to enable STP but it tells me that there is no spanning tree protocol enable, i am using a switch layer 3, and i am wondering, if i have to creat a vlan, and assigne STP on interface level ? sorry for the basic question. i am new to networking.

A layer-3 switch is a layer-2 switch with added routing functionality - for L2, both behave exactly alike. However, when you create a _routed or L3 port_ that port cannot participate in STP.

STP is required when a layer-2 network has redundant links (otherwise a bridge loop is created, causing a broadcast storm).