Switch 7700 Command reference Guide, v2.0

MSTP Configuration Commands 331
stp interface instance
cost
Syntax
stp interface interface-list instance instance-id cost cost
undo stp interface interface-list instance instance-id cost
View
System view
Parameter
interface-list: Ethernet port list, containing multiple Ethernet ports and
expressed as
interface _list = { { interface_type interface_num |
interface_name } [ to { interface_type interface_num | interface_name } ]
}&<1-10>. For detail descriptions of
interface_type, interface_num and
interface_name parameters, refer to the corresponding descriptions in Port
Command Manual. &<1-10> means that the preceding parameters can be
entered up to 10 times.
instance instance-id: Specifies the spanning tree instance ID, ranging from 0
to 16. The Instance 0 represents CIST.
cost cost: Specifies the path cost of the port, ranging from 1 to 200000.
Description
■ Use the stp interface instance cost command to configure the path cost
of the specified port on the specified STI in system view.,.
■ Use the undo stp interface instance cost command to restore the path
cost to default value.
By default, the path cost of the port on every STI is associated with the port speed.
For details, refer to the table in the configuration guideline.
You may specify the instance-id parameter as 0 to configure CIST path cost of
the port. The path cost has effect on the port role selection. A port can be
configured with different path costs on different MSTIs. Thus the traffic from
different VLANs can run over different physical links, thereby implementing the
VLAN-based load-balancing. MSTP will recalculate the port role and transit its
state, upon the port path cost changes.
The default values of the path cost varies with the different port speeds, as
described in the following table.
Related command: stp instance cost.
Table 28 Cost corresponding to the port speed
Link speed
Recommended
value
Recommended value
range
Value range
10Mbps 2,000 200- 20000 1-200000
100Mbps 200 20-2000 1-200000
1Gbps 20 2-200 1-200000
10G/s 2 2-20 1-200000
Above 10G/s 1 1-2 1-200000