spanning-tree instance cost

Syntax

spanning-tree instance <INSTANCE-ID> cost <PORT-COST>

no spanning-tree instance <INSTANCE-ID> cost [<PORT-COST>]

Description

Sets the individual port cost for an MSTI. The switch uses the path cost to determine which links to use for the active topology of the MSTI (forwarding ports) and which ports to block. The path cost setting for a port can be different on each MSTI to which the port belongs.

The no form of this command sets the port cost for an MSTI to the default value.

Command context

config-if

Parameters

<INSTANCE-ID>

Specifies the MSTI number. Range: 1-64.

<PORT-COST>
Specifies the cost of the port for the MSTI. Range: 1-200000000. Default value is calculated from the port link speed:
  • 10 Mbps link speed equals a path cost of 2000000.

  • 100 Mbps link speed equals a path cost of 200000.

  • 1 Gbps link speed equals a path cost of 20000.

Authority

Administrators or local user group members with execution rights for this command.

Examples

On the 6400 Switch Series, interface identification differs.

Setting the port 1/1/1 cost for MSTI 1 to 2000:

switch(config)# interface 1/1/1
switch(config-if)# spanning-tree instance 1 cost 2000

Setting the port 1/1/1 cost for MSTI 1 to the default:

switch(config)# interface 1/1/1
switch(config-if)# no spanning-tree instance 1 cost