3Com Switch 7750 SeriesCommand Reference Guide – MSTP Chapter 1 MSTP Configuration Commands1-19DescriptionUse the stp interface cost command to set the path cost(s) of the specified port(s) in aspecified spanning tree instance in system view.Use the undo stp interface cost command to revert to the default path cost(s) of thespecified port(s) in the specified spanning tree instance in system view.By default, a switch automatically calculates the path costs of a port in differentspanning tree instances based on a specified standard.If you specify the instance-id argument to be 0 or do not specify this argument, the stpinterface cost command sets the path cost(s) of the specified port(s) in the CIST.The path costs of a port in spanning tree instances affect the roles of the ports in thespanning tree instances. By configuring different path costs for the same port indifferent MSTIs, you can make flows of different VLANs traveling along differentphysical links, so as to achieve VLAN-based load balancing. Changing the path cost ofa port in a spanning tree instance may change the role of the port in the instance andput it in state transition.The default port path cost differs with port speed. Refer to Table 1-4 for details.Related command: stp cost.Example# Set the path cost of Ethernet1/0/3 port in spanning tree instance 2 to 400 in systemview.<3Com> system-viewSystem View: return to User View with Ctrl+Z.[3Com] stp instance 2 interface Ethernet 1/0/3 cost 4001.1.18 stp interface edged-portSyntaxstp interface interface-list edged-port { enable | disable }undo stp interface interface-list edged-portViewSystem viewParameterinterface-list: Ethernet port list. You can specify multiple Ethernet ports by providing thisargument in the form of interface-list = { interface-type interface-number [ tointerface-type interface-number ] } &<1-10>, where &<1-10> means that you canprovide up to 10 port indexes/port index ranges for this argument.enable: Configures the specified Ethernet ports to be edge ports.
