59Spanning tree configuration task listsBefore configuring a spanning tree, you must determine the spanning tree protocol to be used (STP, RSTP,PVST, or MSTP) and plan the device roles (the root bridge or leaf node).NOTE:• If GVRP and a spanning tree protocol are enabled on a device at the same time, GVRP packets areforwarded along the CIST. To advertise a certain VLAN within the network through GVRP, make surethat this VLAN is mapped to the CIST when you configure the VLAN-to-instance mapping table. Formore information about GVRP, see the chapter "GVRP configuration."• The spanning tree configurations are mutually exclusive with RRPP and Smart Link.• The spanning tree configurations made in system view take effect globally. Configurations made inEthernet interface view take effect on the interface only. Configurations made in port group view takeeffect on all member ports in the port group. Configurations made in Layer 2 aggregate interface viewtake effect only on the aggregate interface. Configurations made on an aggregation member port cantake effect only after the port is removed from the aggregation group.• After you enable a spanning tree protocol on a Layer 2 aggregate interface, the system performsspanning tree calculation on the Layer 2 aggregate interface but not on the aggregation member ports.The spanning tree protocol enable state and forwarding state of each selected member port is consistentwith those of the corresponding Layer 2 aggregate interface.• Though the member ports of an aggregation group do not participate in spanning tree calculation, theports still reserve their spanning tree configurations for participating in spanning tree calculation afterleaving the aggregation group.STP configuration task listComplete the following tasks to configure STP:Task RemarksConfiguring the rootbridgeSetting the spanning tree modeRequiredConfigure the device to workin STP mode.Configuring the root bridge or a secondary rootbridge OptionalConfiguring the device priority OptionalConfiguring the network diameter of a switchednetwork OptionalConfiguring spanning tree timers OptionalConfiguring the timeout factor OptionalConfiguring the maximum port rate OptionalEnabling the output of port state transition information OptionalEnabling the spanning tree feature Required